Feb 1, 2011

How To Identify Gemstones Part 1

This blog post defines and describes one important tool used in gemstone identity verification:  The Spectroscope.  This tool provides information to help identify a gemstone, however, it is only one piece of the puzzle and there are several other tests needed for an accurate conclusion.  I will discuss those tests in follow up posts.

I have a passion for gemstones and find it very interesting to find out all I can about each gem I own and use when making jewelry.  The details give me a clearer awareness of just how to design a piece of jewelry with each stone.

Of course, I first need to be sure that each gemstone is identified correctly and verify this information with the tools available.  If I am selling a piece of gemstone jewelry, it must be correctly identified.  A Ruby must be a genuine Ruby, not just take someone else’s word that it is.  I must note that I have worked hard to find reputable, competent sources for my gemstones and have NEVER had a gem be anything other than exactly what was described!

The most important information needed about an unknown gem is the Refractive Index (RI) and the Specific Gravity (SG).  Accurate RI readings are generally not difficult to achieve with a Refractometer.  Specific Gravity measurements are time consuming and may not be accurate, involving formula calculations and reference charts.  Software designed to make identification more accurate and swifter, called Gemology Tools, makes identifying a gemstone painless and achievable.

Most gem identification requires more than just RI and Specific Gravity and the Spectroscope is often used to make the final determination.  Some stones and many rough stones can be identified with just the Spectroscope.

Every gemstone has specific spectral lines emitted due to their chemical composition.  When a light source is directed at a gem, the light is redirected and in general terms, absorbed or emitted thru the gem.  The Spectroscope is used to record the light leaving the gem and determine what was absorbed or emitted.  This shows, for example, the colors of the rainbow, minus the colors that were absorbed.  These patterns of missing color are then compared to a chart of known gems to identify the material the light is passing thru.

The Spectroscope is the optical device used, and is actually simple to make at home with items you may already own!

Follow this link to see the instructions to build your own Spectroscope.

For a Make at Home High Resolution Spectrograph, follow this link.  It includes a place to upload your file for analysis!!:

Now you are wondering where to find the charts that show the patterns of spectral lines for each gemstone!  There are several great gemology books available with gemstone details and identification techniques.  There are also some helpful links to websites with more information.  Here are a few recommendations:

Gem Identification Made Easy, Fourth Edition: A Hands-on Guide to More Confident Buying & Selling“  by Antoinette Leonard Matlins (Author)


Good Luck!

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