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Gemstone Cuts

Cutting gemstones is a process of turning rough, unpolished stones into gemstones as we know them, so they can be used in jewelry. Cutting gives the stones a specific shape and enables the true color and brilliance of the gem to emerge. Gem cutters generally need over two years of experience to be considered professionals, and it takes many factors to decide which cut would work best for a given rough stone to best hide its imperfections and to bring out its best qualities. Below are the many cuts and shapes that a cutter would be considering from in order to pass on the best value to his customer.

Gemstones may come in a variety of shapes, such as round, pear, square, octagon, oval, heart, and triangular, among many others. Each of these shapes may be fashioned into many different cuts, depending on the jeweler’s choice of exposing the gemstone’s many facets. For example, the square shape may be fashioned into a Princess cut, Radiant cut, Asscher cut and Cushion cut. Gemstone cuts differ in the amount and size of facets carved into the gem’s surface within each category of shapes.

asscher Cut Gem

Asscher

Alternatively called "Square Emerald cut", it is a hybrid of a princess and an emerald cut. It presents with a distinct X in the gemstone’s table and features cropped corners along its four sides. Rather than creating a brilliant faceted pattern, which would bring out the gem’s fire, the "step-cut" facets in this cut maximize the gem’s clarity. This cut was developed by the Asscher brothers in 1902 of Holland and remained popular through the 1920’s. In 2001, the Asscher cut underwent some modifications by Edward and Joop Asscher, resulting in the Modern Asscher or Royal Asscher cut. The newer version increased the number of facets from 58 to 74, and introduced wider corners. The Asscher Cut resurfaced in popularity after appearing on Sex and the City. Since then, many celebrities began wearing Asscher cut engagement rings, such as Jessica Alba, Kate Hudson, Ashlee Simpson, Julia Roberts, Reese Witherspoon, and Gwyneth Paltrow.

baguette Cut Gem

Baguette

Long and rectangular in shape, baguette cut gemstones are a popular choice for accent stones in jewelry. The term Baguette originated from the Italian word "bacchetta", meaning little stick; bacchio, meaning rod, or from the French word baguette, which is an oblong loaf a bread. The cut was created in the 1920-1930’s during the Art Deco and Art Nouveau movements. Because of its clean lines and a modern, geometric look, which deviated sharply from the traditional Round cut, it became instantly popular. Crafted in a "step cut" fashion, its 14 facets have been cut in steps along the edges, resembling a pyramid without its top. Although not as fiery and brilliant as a round cut, these stones are cut to maximize clarity. Since crafting Baguettes requires fewer cuts than other gemstone shapes, it is extremely important to cut them properly, since there are much fewer facets to hide any imperfections. Baguette cut stones can be regular or "tapered", meaning two sides are tapered inward, resembling a trapezoid. The tapered variation works particularly well as side stones to a round centerpiece. Baguette cut stones usually run small in size, often less than one carat. Therefore, they are measured according to their dimensions, and not by carat weight. Their unique shape allows Baguette stones to be set side by side without gaps, unlike round stones, making them indispensable in today’s jewelry industry.

briolette Cut Gem

Briolette

The Briolette cut is a pear or drop-shaped stone with 84 triangular shaped facets covering its entire surface. There is no table, crown, or pavilion. Because of this, the Briolette is the most difficult shape to cut. In fact, a cutter can only cut about 5 to 10 briolettes per day. Although this cut does not burst with fire and brilliance like a modern Round Brilliant cut, but it does reflect light from all of its triangular facets. Its many angles, like tiny chandeliers, contribute to a wonderful display of color and radiance. Briolettes are a popular choice for dangling earrings, because as they dangle and move, they capture the most light. Briolettes usually are not mounted into heavy settings, and because of that, more of the gemstone is exposed to be visible. Most loose briolettes are drilled with a hole through the top, allowing jewelers to insert a hanging wire for earrings so the gem can dangle freely. Other times, a precious metal cap is secured onto the tip of the gemstone allowing the briolette to work as a pendant. The Briolette is believed to have originated in India as early as the 12th century, and then it may have spread to Europe with the famous French trader and traveler Jean-Baptiste Tavernier, who may have brought it with him from India. In fact, some maintain that the term Briolette comes from the French word "Brilliant", meaning sparkling, and "Brignolette", which translates into a "dried plum". Once popular in the 17th century, before the emergence of more modern cuts such as Round Brilliant, many Briolettes were used in tiaras and crowns worn by monarchs, especially during the Victorian, Edwardian, and Art Deco time periods. In addition, Briolettes were a popular choice in earrings, pendants and necklaces of antique and estate jewelry of royalty and aristocrats.

cabachon Cut Gem

Cabachon

A cabochon, alternatively known as "cab", is simply a polished gemstone without any facets. It has a flat bottom and a slightly rounded top. The traditional Cabochon cut is oval in shape, but any shape can be cut Cabochon style. The term originates from the French "caboche", meaning head. Gemstones shaped and polished "en cabochon" date back to early Judaic, Greek and Roman time periods. Cabochons surged in popularity in the late 13th – early 14th century in Europe, well before the advent of modern cutting technology and knowledge of faceting. In fact, this was the only gem fashioning available for a long time other than using gems in their natural crystal shape. Even though today most jewelers prefer faceted styles, certain gemstones are still cut "en cabochon". Those are the ones where the gems’ special characteristics can only be seen when cut in cabochon. Some examples include asterism, or the star effect found in star sapphires and star rubies, chatoyancy, or the cat’s eye effect found in tourmaline, tiger’s eye, chrysoberyl and apatite, iridescence, or the changing of color in certain light or angle, such as an opal, or adularescence, or the milky-bluish luster or glow that emanates from inside the stone when held at a certain light, found in moonstone, rose quartz and agate. Other candidates for Cabochon cut include those that are naturally opaque or with limited transparency, such as turquoise, jade, and agate; those that possess great color but have some inclusions on their surface; or those that are not very durable. Since a Cabochon cut will minimize the appearance of scratches, many jewelers will opt to cut softer gemstones "en cabochon", in order to prevent them from getting scratched in the faceting process.

cushion Cut Gem

(Antique) Cushion

Once referred to as "Old Mine Cut" or "Old European Cut", this cut presents with approximately 64 facets and offers a basic square shape with gently rounded corners, making it look like a couch cushion. It may also be referred as a "Pillow Cut". Just like a Princess cut, this cut maximizes utilizing the raw gem in the best way possible to avoid waste while simultaneously maintaining fabulous gem luster and brilliance. This traditional cut has been around for 200 years, and has been the industry standard before the start of 20th century. Some cushion cuts may appear slightly oval in their shape. In recent years, cushion cut has renewed its popularity, with Miley Cyrus, Jennifer Garner, Ivanka Trump, Giuliana Rancic, and Mena Suvari all sporting Cushion cut engagement rings.

emerald Cut Gem

Emerald

The Emerald Cut is shaped like a rectangle from the top, with trimmed corners. With approximately 50 facets, this particular cut presents with fewer facets than Round or Square cuts. The emphasis here is not so much on the sparkle, but on the gem’s clarity and color. Color tends to show very vividly in Emerald cut gemstones. In lighter colored gemstones, this cut can be quite dazzling with broader and more striking flashes of light, with the light bouncing between the light and dark surfaces of the gem, as if looking into a hall of mirrors. This cut was originally designed for cutting emeralds. Since emeralds occur in nature with numerous inclusions, cutting them is especially difficult due to potential chipping. The Emerald cut addressed those issues by decreasing the amount of force applied during cutting and protecting the stone from breakage. Eventually, this cut was used for diamonds and other gemstones as well. Customers were particularly drawn to this unique and stylish newer style, as its elongated shape looks particularly flattering on a finger. Beyonce, Mariah Carey, Angelina Jolie, Kate Hudson, Eva Longoria and Kim Kardashian were known to have worn Emerald cut engagement rings.

heart Cut Gem

Heart

The heart shaped cut is in essence a pear shaped cut with a cleft at the top. With 59 standard facets, this cut can be very fiery and offer superb sparkle. Symmetry plays a vital role in selecting a good Heart Shaped cut gemstone. The two halves must be perfectly equal, and the cleft should be sharp and distinct and the sides should be slightly rounded. Rarely used as engagement rings, Heart Shaped gemstones remain a popular choice for earrings, pendants, and gemstone solitaire rings.

marquise Cut Gem

Marquise

This football shaped cut is also known as Navette Cut, and is crafted with 57 facets. It is a type of a modified brilliant cut, meaning it was cut to reflect the most light and offer maximum sparkle and color. It’s important to note that if a gem is cut too shallow, the light will pass through the back of the gem thereby reducing its color and sparkle. Striving for perfect symmetry is another important factor in crafting Marquise cut gemstones. The two end points must line up with each other precisely and the two halves of the stone should be perfect copies of each other. This will ensure that the stone sits properly in its setting, minimizing future chipping or breakage. The Marquise cut diamond was commissioned by King Louis XIV of France to present to his love, Marquise de Pompadour. With its long lines and elongated silhouette, it was supposed to resemble her perfectly shaped smile. Furthermore, its elongated shape flatters the finger, making it appear longer and slimmer. In recent years, the Marquise cut has even been set vertically. Catherine Zeta-Jones and Ashlee Simpson both received vertically set Marquise cut diamond engagement rings. Either way, due to its substantial surface area, this cut offers more weight per carat than any other cut and creates the illusion of a larger gemstone

octagon Cut Gem

Octagon

This rectangular cut is another variation of utilizing a "step-cut" approach, where the stone is crafted with rows of wide, flat, concentric facets that resemble steps as if in a staircase along the gemstone’s circumference. The steps in this cut are not equidistant, unlike that of an Emerald cut. The usual number of facets in an Octagon cut is 53. Octagon cut gemstones are ideal in portraying any gemstone’s deep color. It also showcases any inclusions that a gem may have, so it’s important to look for gemstones that are particularly beautiful in color and are free from inclusions when considering the Octagon cut.

oval Cut Gem

Oval

The Oval cut was created by Lazare Kaplan in the late 1950’s – early 1960’s. It presents with an elliptical shape when viewed from the top, and can be described as a hybrid between round and marquise shapes. Crafted with 69 facets, it is a type of a modified brilliant cut, which offers its wearer the brilliance and fire of a round cut gemstone, in a more unique shape. Its elongated silhouette is an added advantage, because it creates the illusion of a larger gemstone, and allows a finger to look longer and slimmer when wearing it. Famous Oval cut engagement rings include the stunning 12 carat oval sapphire ring Kate Middleton received from Prince William, which belonged to his late mother Princess Diana; and a 5 carat oval diamond ring that Katie Holmes received when she married Tom Cruise.

pear Cut Gem

Pear

Fashioned in a shape of a gleaming teardrop, a Pear cut gemstone can be described as a hybrid between an Oval cut and a Marquise cut with a tapered point on one end. It is a type of a modified Round Brilliant cut and therefore offers 71 facets which reflect light beautifully and allow color to showcase dramatically. The first Pear cut diamond was crafted by a Flemish polisher Louis van Berquem of Belgium in 1458. When crafting a Pear cut gemstone, it is important to aim for perfect symmetry. The point should align with the peak of the rounded end. Pear cut gemstones require a special 6 prong setting, with a prong to maintain support for its fragile point. Most women wear the pointed end of the Pear cut gemstone in the direction of the fingernail, although that largely depends on the wearer’s choice. The elongated silhouette of a Pear cut ring lengthens and slims its wearer’s finger, making it an attractive choice not only for earrings and pendants, but for rings as well. Pear cut engagement rings were worn by such celebrities as Katherine Heigl, Avril Lavigne, Bethenny Frankel, and Jessica Simpson.

princess Cut Gem

Princess

Square in shape, this cut is the second most popular cut, right behind the Round Brilliant cut. Actually, it is technically known as "Square modified brilliant", since it is basically a square version of the Round Brilliant cut. It boasts between 58 to 76 facets that bounce light off its surface beautifully, making it a shape with the most sparkle. Its positive attributes are best brought out by light, transparent gemstones. It is a fairly recent cut, having been created in the 1979 by Ygal Perlman, Betzalel Ambar and Israel Itzkowitz of Israel. However, the Princess cut precursor, or the Profile cut was created by Arpad Nagy of London, in 1961. A princess cut gem with the same width in the diameter as a round cut gem will actually have a higher carat weight, because the round cut gem would have had its four corners cut off to make it round. The square cut gem retains 80% of the rough gemstone, while the round cut gem retains only 50%, making it an excellent value for customers and gem cutters alike.

radiant Cut Gem

Radiant

A combination of a Princess and a Cushion cut, this four sided cut was created by Henry Grossbard in 1977. In this trendy cut, a square or an octagon gem gets its four corners cropped in a straight line, instead of nicely rounding them off as in a Cushion cut. It offers the modern square shape without sacrificing the brilliance and fire of a round cut gem. This sophisticated new style became a celebrity favorite, with Hilary Duff, Drew Barrymore, Jennifer Lopez, Jessica Biel, and Khloe Kardashian receiving Radiant cut engagement rings.

round Cut Gem

Round

Alternatively known as "Round Brilliant", "American Ideal" or "American Standard". With 57 facets, this cut is the most efficient in capturing a stone’s brilliance and sparkle. Although there is no single inventor officially responsible for the round cut invention, many sources name Vincenzio Perruzzi, a Venetian cutter from the 18th century. The round cut has undergone many, many transformations over the years in an effort to manipulate the facets in the best way possible to optimize the dispersion of light in a stone. Some of the most notable round cuts include an "Old Single Cut", a "Rounded Single Cut", an "Old European Cut, a "Jubilee Cut", a "Royal Cut", and a "Basic Brilliant Cut" or the "Ideal Cut", or the "Tolkowsky Cut", developed by a Polish mathematician Marcel Tolkowsky in 1919. Tolkowsky obtained his PhD from the University of London on the topic of the round brilliant diamond cut, firmly establishing himself as the father of the modern round cut. His book, The Diamond Design, is used as a benchmark for diamond cutting in North America. He is credited with coining the terms brilliance, fire and sparkle when it comes to evaluating and grading diamonds. Originally developed exclusively for diamonds, the Round Brilliant cut is now widely used for gemstones as well.

trillion Cut Gem

Trillion / Trilliant

Trilliant cut gemstones are triangular in shape. The edges may be slightly rounded or cropped straight in triangular step cuts along its 3 sides. The curved variation of it is usually used for single, solitaire stones, and is also known as trillion or trillion, while the uncurved variation, or Trilliant, is better suited for side stones. This cut is originally thought to be designed in Amsterdam and was later trademarked by the Henry Meyer Diamond Company of New York in 1962. The Trilliant is a type of a round brilliant, and its equilateral form with 31 to 43 sparkly facets is known to maximize brilliance and gemstone color. Symmetry, angles and proportions remain critical to the proper dispersion of light. If set as a solitaire, the Trilliant cut gemstone will require a specialized setting designed to protect its delicate corners. Furthermore, due to the shallow nature of this cut, it will generally show more dust and dirt on its surface than any other cut and any jewelry set with Trilliants will require extra cleaning. Because Trilliant cut gemstones are cut shallow, they tend to create the illusion of appearing larger than their given weight. In addition, Trilliant cut is known to minimize waste of the rough gemstone during the cutting process. These features, along with a truly sophisticated and unique shape, make Trilliants an excellent value, whether set as a solitaire or used as side stones.

z Cut Gem

Buff-Top

This cut combines the elements of both classic cuts – cabochon and faceted. The top is domed in a Cabochon cut, while the bottom contains facets on its pavilion below the girdle. Due to its facets, this cut still maintains a fair amount of brilliance and offers the illusion of depth as one looks into the center of the gem. The Buff Top cut is popular in men’s jewelry, possibly because the smooth and polished dome of the gemstone is much less easily scratched than the surface of faceted gemstones, and therefore offers more durability.
Sours: https://www.jewelsforme.com/gem_and_jewelry_library/gemstone_cuts

Wondering how to cut and polish gemstones by hand? Asking yourself “is it worth investing in tools for cutting and polishing gemstones”? Well, we’ve put together a selection of methods and tools for cutting and polishing gemstones without a machine. So whether you’re just getting a taste for lapidary, you’re trying to introduce it to your business, or your job involves gemstones on an everyday basis – we’ve got some ideas for you.

How to cut and polish gemstones

When you’re just starting out, try these techniques with a larger gemstone that has obvious flat surfaces with minimal dents, as this will make it easier to shape. And focus on creating just a few, large facets as these are easier to polish later on.

How to cut gemstones by hand: using sandpaper

A less technical, precise and a more free-hand way to cut and polish your gemstones – leaving out the tools is ideal for those who are just dabbling in gemstones without looking to sell just yet.

Equipment:

  • Chopping board
  • Wet and dry sandpaper in 4 grits – 180, 400, 600 and 1200
  • Tap water
  • Tea towel

Method:

  1. Lay the lowest grade sandpaper (the 180 grit) out onto the chopping board rough side up. Be sure to work on a stable surface so the chopping board doesn’t move around – you may want to lay down a tea towel underneath the board for further support.
  2. Pour a small amount of water onto the centre of the sandpaper.
  3. Rub the gemstone over the sandpaper and water to create a smooth facet on the stone.
  4. Repeat step 3 to create several facets and form a rough shape for your gemstone.
  5. Once all sides have been completed, grab the 400 grade and repeat the previous steps – making sure that you re-coat the paper and the stone with water in between each stage to avoid cross-contaminating the grits.
  6. Repeat the above with the 600 and 1200 grit paper.
Top tip: Every so often, rub the gemstone in a circular motion rather than back and forth to make sure you get a smooth surface.

How to cut gemstones by hand: with a tool

For those who are looking to introduce more gemstone work into their business but don’t want to invest in a faceting machine, a Dremel hand tool may be the ideal choice. A Dremel is a versatile rotary tool that can be used around the house and in the workshop – and can be used for more than just cutting.

There’s a vast amount of attachments and burrs that can be used for cutting, sanding, buffing and polishing. So with a Dremel engraver tool, carving gemstones is easy – but before you go all in with your precious gemstones, practice on a cheaper alternative to get the technique down first (river stones are an ideal surface to practice on). Here’s a step-by-step guide on how to cut a gemstone with a Dremel:

Equipment:

Method:

  1. Use a fine tip marker to draw your desired shape onto your gemstone.
  2. Secure the gemstone in a vice or clamp to make sure it’s steady and to avoid the tips of your fingers from getting too close to the cutting wheel.
  3. Hold the Dremel tool firmly by the rubber grip before turning it on and choosing a speed that you feel comfortable with.

Note: If you set the speed higher, it will cut deeper and may damage the stone – so it’s wise to start slow until you get a feel for the tool.

  1. Carve along the marker line by dragging the tip of the Dremel attachment over the design.

Top tip: Don’t hold the tool in one spot for too long as you’ll cut deeper than you intend to and will cause a hole to form.

Find out more about how to use a Dremel rotary tool.

How to polish gemstones without a tumbler

Once you’ve cut your gemstone down to size, the next step is to polish it to a mirror-like finish – allowing the light to bounce off it as it hangs from a necklace or sits in a ring. For a one-off project, you will need:

Equipment:

Check out our range of polishing materials for more.

Method:

  1. Wrap a clean cloth around a chopping board.
  2. Add a small amount of polish to the centre of the board.
  3. Getting a good grip on your stone, rub the sides into the polish on the board – and repeat until the whole stone has been polished.

Top tip: Every so often, wipe the excess polish from the stone to check your progress, adding more as you go if you haven’t reached the desired finish.

But if you already own or are investing in a hand drill tool (powered by battery or pendant motor), you can purchase polishing accessories that will help to get this job done a little bit quicker. Here’s how:

  1. Remove the sanding/cutting attachment and replace with one for polishing, locking it in place.
  2. Apply your polishing compound to the wheel and then buff and polish the surface of your stone until you’re happy with the finish.
  3. Remove any residue of the polishing compound from the wheel and continue to polish your stone until it’s clean and at your desired finish.

So, is it worth investing in tools for cutting and polishing gemstones?

Yes, if you’ll use them frequently. And it may also depend on whether you’re creating the pieces to sell or not – because a higher quality finish may be more achievable when you have the right tools. If you’re only experimenting and it’s unlikely that you’ll develop a stock offering in lapidary, it’s probably best to stick to the low-cost alternative. Or if you’ve been asked to produce a bespoke gemstone piece, it may be worth outsourcing this service as a one-off.

But if you’re looking to introduce gemstones into more of your jewellery designs, investing in the proper tools for cutting and polishing gemstones is the right way to go – be that a hand drill or pendant motor. As outsourcing every piece will add up and can get to be quite costly.

Find everything you need for your next jewellery making project at Cooksongold – from jewellery tools to bullion.

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Author: Cooksongold
Sours: https://www.cooksongold.com/blog/learn/how-to-cut-and-polish-gemstones-by-hand/
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Gemstone

Piece of mineral crystal used to make jewelry

Several terms redirect here. For other uses, see Gemstone (disambiguation), Gem (disambiguation), Gems (disambiguation), Jewels (disambiguation) and Precious Stone (disambiguation).

Group of precious and semiprecious stones—both uncut and faceted—including (clockwise from top left) diamond, uncut synthetic sapphire, ruby, uncut emerald, and amethystcrystal cluster.

A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineralcrystal which, in cut and polished form, is used to make jewelry or other adornments.[1][2][3] However, certain rocks (such as lapis lazuli and opal) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone.

Apart from jewelry, from earliest antiquity engraved gems and hardstone carvings, such as cups, were major luxury art forms. A gem maker is called a lapidary or gemcutter; a diamond cutter is called a diamantaire.

Characteristics and classification[edit]

The traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious; similar distinctions are made in other cultures. In modern use the precious stones are diamond, ruby, sapphire and emerald, with all other gemstones being semi-precious.[4] This distinction reflects the rarity of the respective stones in ancient times, as well as their quality: all are translucent with fine color in their purest forms, except for the colorless diamond, and very hard, with hardnesses of 8 to 10 on the Mohs scale. Other stones are classified by their color, translucency, and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets are relatively inexpensive, a green garnet called tsavorite can be far more valuable than a mid-quality emerald.[5] Another unscientific term for semi-precious gemstones used in art history and archaeology is hardstone. Use of the terms 'precious' and 'semi-precious' in a commercial context is, arguably, misleading in that it deceptively implies certain stones are intrinsically more valuable than others, which is not necessarily the case.

In modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition. For example, diamonds are made of carbon (C) and rubies of aluminium oxide (Al
2O
3). Many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. For example, diamonds, which have a cubic crystal system, are often found as octahedrons.

Gemstones are classified into different groups, species, and varieties.[6][self-published source?] For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow) and morganite (pink), which are all varieties of the mineral species beryl.

Gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture and luster. They may exhibit pleochroism or double refraction. They may have luminescence and a distinctive absorption spectrum.

Material or flaws within a stone may be present as inclusions.

Gemstones may also be classified in terms of their "water". This is a recognized grading of the gem's luster, transparency, or "brilliance".[7] Very transparent gems are considered "first water", while "second" or "third water" gems are those of a lesser transparency.[8]

Value[edit]

Enamelled gold, amethyst, and pearl pendant, about 1880, Pasquale Novissimo (1844–1914), V&A Museum number M.36-1928

Gemstones have no universally accepted grading system. Diamonds are graded using a system developed by the Gemological Institute of America (GIA) in the early 1950s. Historically, all gemstones were graded using the naked eye. The GIA system included a major innovation: the introduction of 10x magnification as the standard for grading clarity. Other gemstones are still graded using the naked eye (assuming 20/20 vision).[9]

A mnemonic device, the "four Cs" (color, cut, clarity, and carats), has been introduced to help describe the factors used to grade a diamond.[10] With modification, these categories can be useful in understanding the grading of all gemstones. The four criteria carry different weights depending upon whether they are applied to colored gemstones or to colorless diamonds. In diamonds, the cut is the primary determinant of value, followed by clarity and color. The ideal cut diamond will sparkle, to break down light into its constituent rainbow colors (dispersion), chop it up into bright little pieces (scintillation), and deliver it to the eye (brilliance). In its rough crystalline form, a diamond will do none of these things; it requires proper fashioning and this is called "cut". In gemstones that have color, including colored diamonds, the purity, and beauty of that color is the primary determinant of quality.

Physical characteristics that make a colored stone valuable are color, clarity to a lesser extent (emeralds will always have a number of inclusions), cut, unusual optical phenomena within the stone such as color zoning (the uneven distribution of coloring within a gem) and asteria (star effects). Ancient Greeks, for example, greatly valued asteria gemstones, which they regarded as powerful love charms, and Helen of Troy was supposed to have worn star-corundum.[11][failed verification]

Aside from the diamond, ruby, sapphire, and emerald, the pearl (not, strictly speaking, a gemstone) and opal[12] have also been considered[by whom?] to be precious. Up to the discoveries of bulk amethyst in Brazil in the 19th century, amethyst was considered a "precious stone" as well, going back to ancient Greece. Even in the last century certain stones such as aquamarine, peridot and cat's eye (cymophane) have been popular and hence been regarded as precious.

Today the gemstone trade no longer makes such a distinction.[13] Many gemstones are used in even the most expensive jewelry, depending on the brand-name of the designer, fashion trends, market supply, treatments, etc. Nevertheless, diamonds, rubies, sapphires, and emeralds still have a reputation that exceeds those of other gemstones.[14]

Rare or unusual gemstones, generally understood to include those gemstones which occur so infrequently in gem quality that they are scarcely known except to connoisseurs, include andalusite, axinite, cassiterite, clinohumite and red beryl.[15]

Gemstone pricing and value are governed by factors and characteristics in the quality of the stone. These characteristics include clarity, rarity, freedom from defects, the beauty of the stone, as well as the demand for such stones. There are different pricing influencers for both colored gemstones, and for diamonds. The pricing on colored stones is determined by market supply-and-demand, but diamonds are more intricate.[citation needed] Diamond value can change based on location, time, and on the evaluations of diamond vendors.[16][failed verification]

Proponents of energy medicine also value gemstones on the basis of alleged healing powers.[17]

Grading[edit]

There are a number of laboratories which grade and provide reports on gemstones.[13]

  • Gemological Institute of America (GIA), the main provider of education services and diamond grading reports
  • International Gemological Institute (IGI), independent laboratory for grading and evaluation of diamonds, jewelry, and colored stones
  • Hoge Raad Voor Diamant (HRD Antwerp), The Diamond High Council, Belgium is one of Europe's oldest laboratories; its main stakeholder is the Antwerp World Diamond Centre
  • American Gemological Society (AGS) is not as widely recognized nor as old as the GIA
  • American Gem Trade Laboratory which is part of the American Gem Trade Association (AGTA), a trade organization of jewelers and dealers of colored stones
  • American Gemological Laboratories (AGL), owned by Christopher P. Smith
  • European Gemological Laboratory (EGL), founded in 1974 by Guy Margel in Belgium
  • Gemmological Association of All Japan (GAAJ-ZENHOKYO), Zenhokyo, Japan, active in gemological research
  • The Gem and Jewelry Institute of Thailand (Public Organization) or GIT, Thailand's national institute for gemological research and gem testing, Bangkok[18]
  • Gemmology Institute of Southern Africa, Africa's premium gem laboratory
  • Asian Institute of Gemological Sciences (AIGS), the oldest gemological institute in South East Asia, involved in gemological education and gem testing
  • Swiss Gemmological Institute (SSEF), founded by Henry Hänni, focusing on colored gemstones and the identification of natural pearls
  • Gübelin Gem Lab, the traditional Swiss lab founded by Eduard Gübelin
  • Institute for Gems and Gold Research of VINAGEMS (Vietnam), founded by Dr. Van Long Pham[citation needed]

Each laboratory has its own methodology to evaluate gemstones. A stone can be called "pink" by one lab while another lab calls it "padparadscha". One lab can conclude a stone is untreated, while another lab might conclude that it is heat-treated.[13] To minimize such differences, seven of the most respected labs, AGTA-GTL (New York), CISGEM (Milano), GAAJ-ZENHOKYO (Tokyo), GIA (Carlsbad), GIT (Bangkok), Gübelin (Lucerne) and SSEF (Basel), have established the Laboratory Manual Harmonisation Committee (LMHC), for the standardization of wording reports, promotion of certain analytical methods and interpretation of results. Country of origin has sometimes been difficult to determine, due to the constant discovery of new source locations. Determining a "country of origin" is thus much more difficult than determining other aspects of a gem (such as cut, clarity, etc.).[19]

Gem dealers are aware of the differences between gem laboratories and will make use of the discrepancies to obtain the best possible certificate.[13]

Cutting and polishing[edit]

Raw sapphire stones stored in a rural commercial cutting plant in Thailand.

A few gemstones are used as gems in the crystal or other forms in which they are found. Most, however, are cut and polished for usage as jewelry. The two main classifications are stones cut as smooth, dome-shaped stones called cabochons, and stones which are cut with a faceting machine by polishing small flat windows called facets at regular intervals at exact angles.

Stones which are opaque or semi-opaque such as opal, turquoise, variscite, etc. are commonly cut as cabochons. These gems are designed to show the stone's color or surface properties as in opal and star sapphires. Grinding wheels and polishing agents are used to grind, shape and polish the smooth dome shape of the stones.[20]

Gems that are transparent are normally faceted, a method that shows the optical properties of the stone's interior to its best advantage by maximizing reflected light which is perceived by the viewer as sparkle. There are many commonly used shapes for faceted stones. The facets must be cut at the proper angles, which varies depending on the optical properties of the gem. If the angles are too steep or too shallow, the light will pass through and not be reflected back toward the viewer. The faceting machine is used to hold the stone onto a flat lap for cutting and polishing the flat facets.[21] Rarely, some cutters use special curved laps to cut and polish curved facets.

Colors[edit]

Nearly 300 variations of diamond color exhibited at the Aurora displayat the Natural History Museum in London.
A variety of semiprecious stones

The color of any material is due to the nature of light itself. Daylight, often called white light, is all of the colors of the spectrum combined. When light strikes a material, most of the light is absorbed while a smaller amount of a particular frequency or wavelength is reflected. The part that is reflected reaches the eye as the perceived color. A ruby appears red because it absorbs all the other colors of white light while reflecting the red.

A material which is mostly the same can exhibit different colors. For example, ruby and sapphire have the same primary chemical composition (both are corundum) but exhibit different colors because of impurities. Even the same named gemstone can occur in many different colors: sapphires show different shades of blue and pink and "fancy sapphires" exhibit a whole range of other colors from yellow to orange-pink, the latter called "padparadscha sapphire".[22]

This difference in color is based on the atomic structure of the stone. Although the different stones formally have the same chemical composition and structure, they are not exactly the same. Every now and then an atom is replaced by a completely different atom, sometimes as few as one in a million atoms. These so-called impurities are sufficient to absorb certain colors and leave the other colors unaffected.

For example, beryl, which is colorless in its pure mineral form, becomes emerald with chromium impurities. If manganese is added instead of chromium, beryl becomes pink morganite. With iron, it becomes aquamarine.

Some gemstone treatments make use of the fact that these impurities can be "manipulated", thus changing the color of the gem.[6]

Treatment[edit]

Gemstones are often treated to enhance the color or clarity of the stone. Depending on the type and extent of treatment, they can affect the value of the stone. Some treatments are used widely because the resulting gem is stable, while others are not accepted most commonly because the gem color is unstable and may revert to the original tone.[23]

Heat[edit]

Heat can either improve or spoil gemstone color or clarity. The heating process has been well known to gem miners and cutters for centuries, and in many stone types heating is a common practice. Most citrine is made by heating amethyst, and partial heating with a strong gradient results in "ametrine" – a stone partly amethyst and partly citrine. Aquamarine is often heated to remove yellow tones, or to change green colors into the more desirable blue, or enhance its existing blue color to a deeper blue.[24]

Nearly all tanzanite is heated at low temperatures to remove brown undertones and give a more desirable blue / purple color.[25] A considerable portion of all sapphire and ruby is treated with a variety of heat treatments to improve both color and clarity.

When jewelry containing diamonds is heated (for repairs) the diamond should be protected with boric acid; otherwise, the diamond (which is pure carbon) could be burned on the surface or even burned completely up. When jewelry containing sapphires or rubies is heated, those stones should not be coated with boracic acid (which can etch the surface) or any other substance. They do not have to be protected from burning, like a diamond (although the stones do need to be protected from heat stress fracture by immersing the part of the jewelry with stones in the water when metal parts are heated).

Radiation[edit]

Virtually all blue topaz, both the lighter and the darker blue shades such as "London" blue, has been irradiated to change the color from white to blue. Most greened quartz (Oro Verde) is also irradiated to achieve the yellow-green color. Diamonds are irradiated to produce fancy-color diamonds (which can occur naturally, though rarely in gem quality).

Waxing/oiling[edit]

Emeralds containing natural fissures are sometimes filled with wax or oil to disguise them. This wax or oil is also colored to make the emerald appear of better color as well as clarity. Turquoise is also commonly treated in a similar manner.

Fracture filling[edit]

Fracture filling has been in use with different gemstones such as diamonds, emeralds, and sapphires. In 2006 "glass-filled rubies" received publicity. Rubies over 10 carats (2 g) with large fractures were filled with lead glass, thus dramatically improving the appearance (of larger rubies in particular). Such treatments are fairly easy to detect.

Synthetic and artificial gemstones[edit]

Synthetic gemstones are distinct from imitation or simulated gems.

Synthetic gems are physically, optically, and chemically identical to the natural stone, but are created in a laboratory.[26] Imitation or simulated stones are chemically different from the natural stone, but may appear quite similar to it; they can be more easily manufactured synthetic gemstones of a different mineral (spinel), glass, plastic, resins, or other compounds.

Examples of simulated or imitation stones include cubic zirconia, composed of zirconium oxide, synthetic moissanite, and un-colored, synthetic corundum or spinels; all of which are diamond simulants. The simulants imitate the look and color of the real stone but possess neither their chemical nor physical characteristics. In general, all are less hard than diamond. Moissanite actually has a higher refractive index than diamond, and when presented beside an equivalently sized and cut diamond will show more "fire".

Cultured, synthetic, or "lab-created" gemstones are not imitations: The bulk mineral and trace coloring elements are the same in both. For example, diamonds, rubies, sapphires, and emeralds have been manufactured in labs that possess chemical and physical characteristics identical to the naturally occurring variety. Synthetic (lab created) corundum, including ruby and sapphire, is very common and costs much less than the natural stones. Small synthetic diamonds have been manufactured in large quantities as industrial abrasives, although larger gem-quality synthetic diamonds are becoming available in multiple carats.[27]

Whether a gemstone is a natural stone or synthetic, the chemical, physical, and optical characteristics are the same: They are composed of the same mineral and are colored by the same trace materials, have the same hardness and density and strength, and show the same color spectrum, refractive index, and birefringence (if any). Lab-created stones tend to have a more vivid color since impurities common in natural stones are not present in the synthetic stone. Synthetics are made free of common naturally occurring impurities that reduce gem clarity or color unless intentionally added in order to provide a more drab, natural appearance, or to deceive an assayer.[citation needed] On the other hand, synthetics often show flaws not seen in natural stones, such as minute particles of corroded metal from lab trays used during synthesis.

List of rare gemstones[edit]

  • Painite was discovered in 1956 in Ohngaing in Myanmar. The mineral was named in honor of the British gemologist Arthur Charles Davy Pain. In 2005, painite was described by the Guinness Book of World Records as the rarest gem mineral on earth.[28][page needed]
  • Hibonite was discovered in 1956 in Madagascar. It was named after the discoverer the French geologist Paul Hibon. Gem quality hibonite has been found only in Myanmar.[29]
  • Red beryl or bixbite was discovered in an area near Beaver, Utah in 1904 and named after the American mineralogist Maynard Bixby.
  • Jeremejevite was discovered in 1883 in Russia and named after its discoverer, Pawel Wladimirowich Jeremejew (1830–1899).
  • Chambersite was discovered in 1957 in Chambers County, Texas, US, and named after the deposit's location.
  • Taaffeite was discovered in 1945. It was named after the discoverer, the Irish gemologist Count Edward Charles Richard Taaffe.
  • Musgravite was discovered in 1967 in the Musgrave Mountains in South Australia and named for the location.
  • Grandidierite was discovered by Antoine François Alfred Lacroix (1863–1948) in 1902 in Tuléar Province, Madagascar. It was named in honor of the French naturalist and explorer Alfred Grandidier (1836–1912).
  • Poudretteite was discovered in 1965 at the Poudrette Quarry in Canada and named after the quarry's owners and operators, the Poudrette family.
  • Serendibite was discovered in Sri Lanka by Sunil Palitha Gunasekera in 1902 and named after Serendib, the old Arabic name for Sri Lanka.
  • Zektzerite was discovered by Bart Cannon in 1968 on Kangaroo Ridge near Washington Pass in Okanogan County, Washington, USA. The mineral was named in honor of mathematician and geologist Jack Zektzer, who presented the material for study in 1976.

See also[edit]

References[edit]

  1. ^"Gemstone". Lexico. Oxford University Press.
  2. ^Webster Online DictionaryArchived 2007-06-03 at the Wayback Machine
  3. ^Alden, Nancy (2009). Simply Gemstones: Designs for Creating Beaded Gemstone Jewelry. New York, NY: Random House. p. 136. ISBN .
  4. ^Bauer, Max (1968). Precious Stones. Dover Publications. p. 2. ISBN .
  5. ^Wise, R. W., 2006, Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones, Brunswick House Pr, pp. 3–8 ISBN 0-9728223-8-0
  6. ^ abFrangoulis, George (18 April 2015). GEM HUNTER. Lulu.com. ISBN .[self-published source]
  7. ^AskOxford.com Concise Oxford English dictionary online.[full citation needed]
  8. ^Desirable diamonds: The world's most famous gem. by Sarah Todd.[full citation needed]
  9. ^Wise, R. W., 2006, Secrets of The Gem Trade, The Connoisseur's Guide To Precious Gemstones, Brunswick House Pr, p.36 ISBN 0-9728223-8-0
  10. ^Wise, R. W., 2006, Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones, Brunswick House Pr, p. 15
  11. ^Burnham, S.M. (1868). Precious Stones in Nature, Art and Literature. Bradlee Whidden. Page 251 URL: Helen of Troy and star corundumArchived 2010-10-13 at the Wayback Machine
  12. ^Church, A.H. (1905). "Definition of Precious Stones". Precious Stones considered in their scientific and artistic relations. His Majesty's Stationery Office, Wyman & Sons. p. 11. Archived from the original on 2007-09-29 – via Farlang.com.
  13. ^ abcd Secrets of the Gem Trade; The Connoisseur's Guide to Precious Gemstones, Richard W Wise, Brunswick House Press, Lenox, Massachusetts., 2003
  14. ^"5 Most Precious Stones". HowStuffWorks.com. 2009-11-09. Archived from the original on 2014-11-06.
  15. ^"A complete guide to Gemstones". Jewellery Monthly. 2015-04-02. Archived from the original on 2017-08-28.
  16. ^"Artificial treatment of gemstones". Dictionary of Gems and Gemology. Berlin, Heidelberg: Springer Berlin Heidelberg. 2009. pp. 50. doi:10.1007/978-3-540-72816-0_1308. ISBN .
  17. ^Katz, Michael (2005). Gemstone Energy Medicine: Healing Body, Mind and Spirit. Natural Healing Press. ISBN . Retrieved 2020-04-06.
  18. ^"The Gem and Jewelry Institute of Thailand (Public Organization)". Bangkok Post.
  19. ^"Rapaport report of ICA Gemstone Conference in Dubai". Diamonds.net. 2007-05-16. Archived from the original on 2011-07-26. Retrieved 2010-07-30.
  20. ^Kraus, Pansy D. (2007). Introduction to Lapidary. Krause Publications. ISBN .
  21. ^Vargas, Glenn; Vargas, Martha (2002). Faceting For Amateurs. ISBN .
  22. ^"Padparadscha Sapphires: 10 Tips On Judging The Rare Gem". The Natural Sapphire Company Blog. 2015-04-06. Retrieved 2018-01-19.
  23. ^Gemstone Enhancement: History, Science and State of the Art by Kurt Nassau
  24. ^Nassau, Kurt (1994). Gem Enhancements. Butterworth Heineman.
  25. ^"Tanzanite heating – the science". Archived from the original on 20 June 2016.
  26. ^Jewelers' circular-keystone: JCK. Chilton Company. 1994.[full citation needed]
  27. ^"New process promises bigger, better diamond crystals". Carnegie Institution for Science. Archived from the original on 1 December 2010. Retrieved 7 January 2011.
  28. ^Folkard, Claire; Freshfield, Jackie; Masson, Carla; Dimery, Rob (12 December 2017). Guinness World Records 2005. Guinness World Records Limited. ISBN .
  29. ^Hainschwang, Thomas; Notari, Franck; Massi, Laurent; Armbruster, Thomas; Rondeau, Benjamin; Fritsch, Emmanuel; Nagashima, Mariko (Summer 2010). "Hibonite: A New Gem Mineral"(PDF). Gems & Gemology. 46 (2): 135–138. doi:10.5741/GEMS.46.2.135.

External links[edit]

Wikiquote has quotations related to: Gemstone
Wikimedia Commons has media related to Gemstones.
Look up gemstones in Wiktionary, the free dictionary.
Sours: https://en.wikipedia.org/wiki/Gemstone
How to Cut Gemstones - Opal Faceting in 4K

How to Polish Rocks & Gems Without a Rock Tumbler

The excitement of turning a jagged piece of stone into a gleaming gem or rock motivates rock hounds to polish stone after stone. Polishing rocks is a satisfying hobby, but the use of a rock tumbler to achieve the polished result is surprisingly unnecessary. With a few simple materials and some elbow grease, even the most novice rock hound can create beautiful polished stones and gems from a jagged collection.

Cleaning the Stones

Fill a bucket with hot, soapy water and clean away all the dirt and residue from the rocks. Use an old toothbrush to get into any crevices and to remove stubborn bits of dirt or grime.

Grinding the Stones

Use a handheld rotary tool, often called a dremel tool, to begin grinding the stones and gems into shape. Make sure you are wearing protective eye wear and gloves for this. Grind down sharp edges and crevices to help make sanding the stones and gems a little easier.

Sanding the Stones

Sand the stones and gems for shaping. Begin with a coarse grain of sandpaper, and moisten the paper with water. Begin sanding until most of the rough edges begin to become smooth and rounded or until you see the desired shape of the rock. Be discriminating with your grain of sandpaper, as some stones and gems are softer than others. You may find that softer gems or stones do not require the coarsest grain of sandpaper.

Sand the stones and gems again to prepare them for polishing. Begin with a medium grain sandpaper, and sand the rock down to both its desired shape and smoothness. As you see your desired results, use lighter grain sandpaper, finishing with ultra-fine grain.

Polishing the Stones

Apply the finishing polish to the stones and gems. Using a heavy fabric such as denim, polish the rocks until they begin to shine or show luster. At this point, you may choose to either continue polishing with the cloth, or you may coat the stones and gems with mineral oil or commercial rock polish. Allow them to dry.

Sours: https://sciencing.com/polish-rocks-gems-rock-tumbler-8164627.html

Gems smooth

The Smooth Gem is an item in A Link Between Worlds.[1] As its name implies, it is characterized by its irresistible smoothness.[2]

Location and Uses

The sprite for the Smooth Gem

The Smooth Gem is a mystical stone used by the Zora Queen, Oren, to contain her powers and prevent herself from growing gigantic.[3]

After Yuga seals Hyrule Castle, Link is able to travel to Zora's Domain, where he discovers that the Queen's gem was stolen by the Shady Guy.[4] Link must track the thief to Kakariko Village and confront him. Explaining that he was unaware of the Smooth Gem's importance, the Shady Guy gives Link the Pegasus Boots out of remorse,[5] but is unable to return the Smooth Gem because he has already sold it to the Street Merchant.[6] In order to return it to Oren, Link must purchase it for 200 Rupees and present it to her in Zora's Domain. Afterwards, Oren rewards him with the Zora's Flippers out of gratitude.

Nomenclature

References

  1. Encyclopedia (Dark Horse Books) pg. 139
  2. ↑"Man, did that stone ever feel smooth. I tell you, smooth as a--! Ugh, I gotta forget about that thing!" — Shady Guy (A Link Between Worlds)
  3. ↑"That finless jerk probably thought it was just some sparkly thing! But the queen needs it to contain her power! Without that smooth gem, our queen will keep--! [...] She'll keep bloating up!" — Zora Underling (A Link Between Worlds)
  4. ↑"It's getting worse by the second! I can't believe that guy came in and stole the smooth gem right out from under our gills!" — Zora Underling (A Link Between Worlds)
  5. ↑"I couldn't help taking it. My boots help me run so fast that I've been stealing everything that isn't nailed down! But here, you take these boots. I can tell that you won't abuse their power. I hope they fit." — Shady Guy (A Link Between Worlds)
  6. ↑"I knew that gemstone would fetch a high price. I-I'm sorry. I already sold it. To that guy over there. I already spent all the money I got from selling that darn stone." — Shady Guy (A Link Between Worlds)
Sours: https://zelda.fandom.com/wiki/Smooth_Gem
The Most SATISFYING Thing You’ve Never Heard Of! A Beginner’s Guide to Rock Tumbling

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