Thursday, August 11, 2011
How to Select Raw Gems
eHow Hobbies, Games & Toys Editor
This article was created by a professional writer and edited by experienced copy editors, both qualified members of the Demand Media Studios community. All articles go through an editorial process that includes subject matter guidelines, plagiarism review, fact-checking, and other steps in an effort to provide reliable information.
If you plan to cut your own stones or are looking for a less expensive way to add gems to your collection, you may wish to purchase raw gems. Since these gems are not cut, the quality may not be so obvious, so you will need to be careful when you select raw gems.
- Difficulty:
- Easy
Instructions
Things You'll Need
- Loupe
- 1 Decide how you will use the raw gem. Some raw gems are attractive mounted with minimal cutting or polishing. If you plan to use the rough stone in jewelry, you will want to select a stone that looks good to the naked eye. Since imperfections will not be cut or polished out, avoid deep cuts, gouges and scratches.
- 2 Use a loupe to see imperfections hidden from the naked eye. The loupe magnifies the gemstone, allowing small details to be seen.
- 3 Choose gems valued correctly for your project. If you are new to cutting gems, you should start with less expensive stones that will not cost you a fortune to replace. Quartz is a good choice for beginners and is available in slabs that are easy to finish.
- 4 Pick higher quality gems as your cutting skills increase. After you have practiced for a while and become comfortable with the machine, move to garnets. Garnets are still relatively inexpensive, but allow for a beautiful finished stone.
- 5 Avoid overly cheap raw gems. If the deal is too good to be true, it probably is. Poor quality gems are hard to cut, not attractive to use in jewelry settings and add little value to a collection. For most transparent stones, the darker they are, the poorer the quality. Study up on what the gem you are purchasing should look like.
- 6 Pick up a copy of the "Handbook of Rocks, Minerals, and Gemstones," by Walter Schumann, from Amazon.com (see Resources below). The book details all kinds of gems with photos of them in their raw and finished state. The book may help you select better quality raw materials.
- 1
Tips & Warnings
- For the best value, you should buy large parcels containing a mixed variety of stones in varying quality. One parcel may produce many fine gem stones for collecting or cutting.
- While raw gems may be less inexpensive than cut stones, do not expect to get a great deal on raw diamonds or emeralds. Expensive gems are still expensive in their raw form.
Resources
- "Handbook of Rocks, Minerals, and Gemstones" at Amazon.com
About Raw Gems
Nellie Day is a freelance writer based out of Hermosa Beach, Calif. Her work can regularly be seen on newsstands, where her specialties include weddings, real estate, food and wine, pets, electronics, architecture and design, business and travel. Day earned a master's degree in broadcast journalism from the University of Southern California.
Raw gems are much like gold in that both items must be hunted, mined and taken in for reshaping. Like gold, raw gems can be difficult to identify in their natural forms. If you're lucky enough to find a precious raw gem or two, however, you may be able to craft the stone into a lovely shape that can be used for a fine piece of custom jewelry for yourself or sold to a jeweler for a sizable price.
Significance
- The finished stones that are set and mounted in fine jewelry pieces are not the same stones that are mined throughout the world. In their raw forms these gems are found inside rock-like nuggets that must be broken open with a miner's pick and cut into smooth and rounded shapes, such as solitaire, emerald, radiant and ascher, that appear in jewelry stores.
Identification
- Raw gems often look like normal rocks, with many jagged edges and asymmetrical shapes. There are a few characteristics, however, that set raw gems apart from standard rocks, stones and other materials. Raw gems are usually colored, and some of that color exudes through to the surface, or shell, of the gem's capsule. Their edges also are a lot sharper and more iridescent than the average stone. Some are even mistaken for glass. If a rock jumps out at you, either because of its size, shape, color or another unique feature, this may be a raw gem. Many raw gems are discovered simply because someone noticed a rock that was unlike others.
Types
- Aside from white raw gems, most gems are colored; so are most raw gems. The most common colors for raw gems are black, blue, orange, green, purple, yellow and red. Popular black raw gems include obsidian, black diamond and onyx. Popular blue raw gems are aquamarine, turquoise and sapphire. Popular orange raw gems are tiger eye, sunstone and carnelian. Popular green raw gems are emerald, jade and peridot. Popular purple raw gems are rose quartz, amethyst and royal azel. Popular yellow raw gems are topaz, citrine and sagenite. Popular red raw gems are ruby, blood opal and garnet. Aside from diamonds, popular white raw gems include quartz, moonstone and white opal.
Misconceptions
- Raw gems look nothing like the stones you see inside jewelry stores. They are dull, unpolished, jagged and may appear discolored. In their natural state, they look more like colorful rocks than gemstones. Even when they are cracked open, the material inside will look more like a colorful crystal than a precious gemstone. Raw gems also are less valuable than the stones that are derived from them. You should not expect to receive a significant amount of money for any raw gems you find. You could, however, take your raw gems to a gem cutter, lapidary, gemologist or jewelry maker who specializes in gemstones in order to have the rough stone cut into a more valuable gem that you could then wear or sell.
Geography
- Though there are a few raw gem mining establishments in the United States, including North Carolina, Alabama, New Mexico, Wisconsin, Hawaii, Florida, Illinois, New Hampshire, New Jersey, Vermont and Washington, and even a few where the general public can go in search of their own raw gems, most of the nation's raw gem supply comes from other countries. Burma/Myanmar, Pakistan, Russia, Africa, China and Australia are the main producers of raw gems.
Gem Stone Identification Steps to Identify Gem Stones!
So, you have a pretty stone, and you want to know just what it is you have! Maybe it's a diamond gem stone, or an emerald gem stone, or maybe it's a close cousin, or even a piece of colored glass. That's where the science, (and art) of gem stone identification comes in.
If you are confused about the identity of your gem stone, don't feel embarrassed. Kings and emperors have made the same kind of mistakes in identifying gem stones themselves.
Take the ruby. It's a deep red crystal, very hard and very beautiful. And very hard to distinguish from its mineralogical cousin, the very beautiful but somewhat less rare spinel.
Chemically very similar, containing only one extra ingredient in its molecular mix, those who would be experts at identification of gem stones have often mistaken the spinel for the ruby. The most famous case of mistaken identity is the Black Prince Ruby, actually a 170 carat spinel, which has been for centuries a part of the Crown Jewels of England.
So, how does one go about identifying gem stones? Well, it takes some training, some special tools, and a lot of patience.
Identifying Gem Stones – Step 1:
First, try to make sure that, the gemstone that you have, is a gem stone. Some times what you think may be a gem stone is just a pretty rock or a piece of metallic ore.
Since the term gem stone is largely arbitrary, this can be hard. Some basic guidelines include:
Identifying Gem Stones – Step 2:Hardness:In the identification of gem stones, hardness is one of the most important of all tests. While not usually a definitive way to identify a gem stone, it does at least put you into the correct group of possibilities.
To help you use hardness to identify a gem stone, there are a variety of hardness scales that you can use. The most common is the 'Mohs' Scale' which ranks mineral hardness on a scale of one (talc) to ten (diamond).
To measure the hardness of the gem stone you wish to identify, you will use a hardness kit. This contains a set of substances of varying hardness keyed to one of the hardness scales.
If your test substance can scratch the subject gem stone, then the test substance is harder than the subject gem stone. By trying several test substances on your subject gem stone, you will be able to approximate the hardness of the subject.
Since diamond is often too expensive for most kits, glass is sometimes used in its place.
Identifying Gem Stones – Step 3:Cleavage:This refers to the tendency of crystals to break along fixed planes in their structure. By striking the crystalline gem stone, you can examine the break and compare it to various cleavage charts.
Many gem stones, including quartz and mica, are easily identified by this way. If you suspect that your gem stone is extremely valuable, like a diamond, you may want to skip this step.
Identifying Gem Stones – Step 4:Streak:This is a method of gem stone identification that involves using the subject gem stone to make a mark on a hard, ceramic plate. Many (but not all) gem stones will leave a streak. By comparing the appearance of this streak to various charts, you have another clue to use in gem stone identification.
Identifying Gem Stones – Step 5:Crystal morphology, or shape.Most gem stones are made up of crystals, each with a unique shape based on their atomic and molecular structure. A simple example of crystal shape can be seen by examining sugar crystals and salt crystals under a powerful glass. While they may look the same in a bowl, up close their crystal shapes are very different and unique.
Identifying Gem Stones – Step 6:Color:While this may seem the first test to use when classifying a gem stone, using color to identify a stone is not as reliable as you might think.
Most people view the sapphire as blue, but this cousin to the ruby can be found in various shades including pink, green, yellow and almost transparent. The classic diamond, with its colorless crystal, looks so much like the less rare cubic zirconium or cubic zirconia, that they almost indistinguishable without a close examination.
Identifying Gem Stones – Step 7:Chemical and Physical tests:These methods of identification of gems most often used by experts because they usually require special equipments. The tests include:
Once you have your list of measurements, and a reliable set of tables for comparison, you are well on your way to identification of your gem stone.
BUT, before you put the down payment on that boat, check with an expert(gemologist who is a person who studies gems and can identify gem stones) to make sure that the shiny stone that you have, is really a diamond, and not a zirconium.
Note: (Please, don't try to identify a gem stone by yourself if you have precious stones and expensive ones, but it's better to check them by a gemologist or send your gem stones to us to check them for you).
If you are confused about the identity of your gem stone, don't feel embarrassed. Kings and emperors have made the same kind of mistakes in identifying gem stones themselves.
Take the ruby. It's a deep red crystal, very hard and very beautiful. And very hard to distinguish from its mineralogical cousin, the very beautiful but somewhat less rare spinel.
Chemically very similar, containing only one extra ingredient in its molecular mix, those who would be experts at identification of gem stones have often mistaken the spinel for the ruby. The most famous case of mistaken identity is the Black Prince Ruby, actually a 170 carat spinel, which has been for centuries a part of the Crown Jewels of England.
So, how does one go about identifying gem stones? Well, it takes some training, some special tools, and a lot of patience.
Identifying Gem Stones – Step 1:
First, try to make sure that, the gemstone that you have, is a gem stone. Some times what you think may be a gem stone is just a pretty rock or a piece of metallic ore.
Since the term gem stone is largely arbitrary, this can be hard. Some basic guidelines include:
- If it's rough and sandy, it should not be identified as a gem stone, no matter how pretty it may be.
- If it's malleable, that is easily able to be shaped by hammering, crushing or bending; it is probably a metallic ore. Gem stones are primarily identified by a crystalline structure, which can be shaped, but not easily shaped and then only by cutting, fracturing or abrasion.
- A pearl, though used in jewelry, is not considered a gem stone. (Though if you want to identify it as a gem stone, go ahead. I won't tell anyone.)
- It is tempting to identify fossilized wood as a gem stone because of its shiny, lustrous surface and its attractive lines and colors, but it is not considered a gem.
Identifying Gem Stones – Step 2:Hardness:In the identification of gem stones, hardness is one of the most important of all tests. While not usually a definitive way to identify a gem stone, it does at least put you into the correct group of possibilities.
To help you use hardness to identify a gem stone, there are a variety of hardness scales that you can use. The most common is the 'Mohs' Scale' which ranks mineral hardness on a scale of one (talc) to ten (diamond).
To measure the hardness of the gem stone you wish to identify, you will use a hardness kit. This contains a set of substances of varying hardness keyed to one of the hardness scales.
If your test substance can scratch the subject gem stone, then the test substance is harder than the subject gem stone. By trying several test substances on your subject gem stone, you will be able to approximate the hardness of the subject.
Since diamond is often too expensive for most kits, glass is sometimes used in its place.
Identifying Gem Stones – Step 3:Cleavage:This refers to the tendency of crystals to break along fixed planes in their structure. By striking the crystalline gem stone, you can examine the break and compare it to various cleavage charts.
Many gem stones, including quartz and mica, are easily identified by this way. If you suspect that your gem stone is extremely valuable, like a diamond, you may want to skip this step.
Identifying Gem Stones – Step 4:Streak:This is a method of gem stone identification that involves using the subject gem stone to make a mark on a hard, ceramic plate. Many (but not all) gem stones will leave a streak. By comparing the appearance of this streak to various charts, you have another clue to use in gem stone identification.
Identifying Gem Stones – Step 5:Crystal morphology, or shape.Most gem stones are made up of crystals, each with a unique shape based on their atomic and molecular structure. A simple example of crystal shape can be seen by examining sugar crystals and salt crystals under a powerful glass. While they may look the same in a bowl, up close their crystal shapes are very different and unique.
Identifying Gem Stones – Step 6:Color:While this may seem the first test to use when classifying a gem stone, using color to identify a stone is not as reliable as you might think.
Most people view the sapphire as blue, but this cousin to the ruby can be found in various shades including pink, green, yellow and almost transparent. The classic diamond, with its colorless crystal, looks so much like the less rare cubic zirconium or cubic zirconia, that they almost indistinguishable without a close examination.
Identifying Gem Stones – Step 7:Chemical and Physical tests:These methods of identification of gems most often used by experts because they usually require special equipments. The tests include:
- Specific gravity.
- Refractive Index.
- Light Dispersion.
- Color changes.
Once you have your list of measurements, and a reliable set of tables for comparison, you are well on your way to identification of your gem stone.
BUT, before you put the down payment on that boat, check with an expert(gemologist who is a person who studies gems and can identify gem stones) to make sure that the shiny stone that you have, is really a diamond, and not a zirconium.
Note: (Please, don't try to identify a gem stone by yourself if you have precious stones and expensive ones, but it's better to check them by a gemologist or send your gem stones to us to check them for you).
Cutting and polishing
A few gemstones are used as gems in the crystal or other form in which they are found. Most however, are cut and polished for usage as jewelry. The picture to the left is of a rural, commercial cutting operation in Thailand. This small factory cuts thousands of carats of sapphire annually. 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 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.[14]
Gems which are transparent are normally faceted, a method which 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.[15] Rarely, some cutters use special curved laps to cut and polish curved facets.
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