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Article: Identifying Stones
One of the most interesting and challenging questions a retailer of semi-precious gems is confronted with is "what stone is this?"
Often the answer is an easy one, either because the stone was ordered specifically by specimen or because it is an easily identifiable species of a particular mineral. For example amethyst is easy to identify because of its purple coloring and relative transparency.

But what about that silver ring with the unusual and beautiful stone you got as part of an assortment from Whirled Planet? Being able to determine the correct stone classification will make the sale easier and will enhance the purchase from the customer's perspective. Most people learn to identify stones through experience. Familiarity with stone types breeds confidence and a working knowledge that can be added to gradually over time.

Some background information is helpful however. Gemologists use several methods to determine a stone type. First and foremost they use primary color as a reference point. Some minerals like azurite or malachite are very consistent in color from specimen to specimen. Other gems like quartz are harder to classify because they come in all colors, depending on what trace minerals are present. Purple amethyst is a kind of quartz with iron present, while rose quartz gets its color from titanium.

Color can also be altered, as it has for millennia, to improve or change the appearance of a stone. Most commercial citrine is actually heated amethyst. In this same category of classification method we can apply the idea of "grain" or texture. The banding found in various agates, or the crystalline nature of various quartz colors lends a certain character to each that is consistent over various colors. The similarities between rainbow moonstone and labradorite are an easily identifiable example of similar feldspars that have completely different primary color.

Gemologists also refer to "streak color" as a means of determining species. Basically, this involves scratching the stone with moderate force on unglazed porcelain as found on the bottom of a dinner plate or floor tile. The color of the streak on the ceramic shows the true color of the stone minus the impurities that cause the coloration. Blue sodalite, for example, will scratch white. This test is used for testing stone rough and will damage set stones, so don't try this with anything you plan to sell! I mention it here for reference purposes only.

Another method gemologists use to classify gems is by testing their hardness. In the 1800's the Moh's hardness scale was developed to stratify all the gems of the world along a scale from one to ten. In practice, the softest stone is talc, with a hardness of one. The hardest stone is diamond, with a rating of ten. A stone of higher hardness will scratch a stone of lesser number on the scale. Quartz, with a hardness of 7, will scratch hematite with a hardness of 4. While you should not try to perform this test on jewelry set in finished form, it is a good idea to know relative harnesses to avoid damaging your inventory.

Quartzes, agates and jaspers are all relatively hard stones (Moh's 6-7), but rhodocrosite (hardness 4, second from right in picture), malachite (3.5 - 4) and fluorite (4) are all stones that should be stored and worn with care.

Beyond these criteria, gemologists may also use density, transparency, refraction, spectral analysis, and fluorescence to unlock a stone's identity. For everyday examination, these methods are beyond the grasp of most of us stone aficionados. We tend to rely on our experience and "go with the gut" when making a questionable identification. Often we will find a customer who knows a particular stone at sight, while just as often a customer will claim to "know a lot about stones" only to mispronounce labradorite or misidentify sodalite as lapis.

Ultimately it can be very difficult to identify a stone based on the small sample set in a pendant or ring. A particular specimen may not be representational of the rest of its family and can thus be difficult to classify. What I do is look at the details of the stone, including its color, grain, inclusional qualities and its overall character, then try to cross reference those pieces of the puzzle mentally with what I know about gemstones from past experience. Obviously the more you know, the better you will get at identifying those hard to classify stones.

If I think they are jasper or agate, I will give the identification with the caveat that I am not 100% sure. I know from my own experience with the products we sell on our site that most unknowns are either agate or jasper, but this rule may not apply to other vendors' merchandise.

When we ship out our pendants or rings by the gram, one of the best ways to order is as an assortment. If you definitely need tiger eye or carnelian (for example), then by all means order by stone. When you order assorted stones, you will almost always get some unusual and exciting stone that you have no idea how to identify. As a rule, we ship these assortments with the following stones:

amethyst, rose quartz, carnelian, onyx, rainbow moonstone, labradorite, sodalite, lapis lazuli, snowflake obsidian, amazonite, dendritic agate, malachite, nephrite jade, chrysocolla, mother of pearl, abalone, rhodonite, rhodocrosite, tiger eye, fluorite, ruby zoisite, assorted jaspers and agates.

This is a partial list. There are many other stones that we get only a few pieces here and there. If you are having trouble identifying stones, there are several good resources I can recommend. Some good websites are: http://www.jewelrymall.com/stones/, http://mineral.galleries.com/minerals/gemstone/class.htm, http://www.minerals.net.

A great book I use all the time is Gemstones of the World by Walter Schumann. It has over 1500 photos and lots of great background. You can buy it http://amazon.com.

If you ever need help identifying a stone or have questions about something you bought from us, don't hesitate to give us a call at 888-408-0072 (808-822-2335 international callers), or drop me an email. I'll always do me best to answer your question in a timely manner.


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According to the surveys we had our customers fill out last month, many people said they wanted to see more "new merchandise." Others said they like to see sale items. We've got both bases covered this month with our new arrivals and our permanent price reductions on many of our regularly stocked designs.

Look for new purses in April, along with more jewelry and textile products. Thanks to everyone that completed our survey in March. We are tabulating the results and you can bet that we will respond to your input.

Last month it was arctic here on Kauai: the temperature dipped down into the low 50's at night! Here's hoping it warms up wherever you are this month...

Aloha,

Mike McGinnis
Whirled Planet
808-822-2335 tel.
888-408-0072 toll free (US only)
http://indiasilver.com/index.asp