How to Identify Gem Stones

Diamond earrings and pendant

Treasured for its beauty, the value of a gemstone depends on four elements: aesthetic beauty of the stone itself, gem scarcity, solidity or density, and cut and polished qualities of the gemstone. Advanced technology makes it difficult to identify gemstones by appearance alone. It requires expertise and knowledge of a certified gemologist or jeweler when selecting or grading a gemstone. Learn the basics on how to identify gemstones.

Things You'll Need

• Gem selection of interest
• Books written for jeweler, professional or amateur gemologist such as "Gemstones" by Cally Hall, "Gem Identification Made Easy: A Hands-On Guide to More Confident Buying and Selling" by Antoinette L. Matlins and Antonio C. Bonanno or "The Jeweler's Directory of Gemstones: A Complete Guide to Appraising and Using Precious Stones from Cut and Color to Shape and Setting" by Judith Crowe
• Names of reputable certified gemologist appraiser

Instructions

1. 

   Research the gemstone of interest. The list of gemstones is extensive but includes, emerald, ruby, sapphire, amethyst, opal, topaz, aquamarine, tanzanite, citrine, garnet, tourmaline, lapis lazuli, jade, zircon, iolite, moonstone, amber, turquoise, coral, agate, onyx, bloodstone, jasper, pearl and diamond. Diamonds, rubies and emeralds have the greater concentration of monetary value. Opals have brilliant areas of color. Star gems such as the star sapphire retain a star-like singularity on its surface.

2. 

   Note the gemstones' unique set of properties. Optical properties include the color of the stone, its measure of refraction, its transparency and the display of prismatic color. Visual inspection or jewelers' loupe is rarely sufficient for authenticity due to the advancement of replication. Determine color quality by the combination of hue, tone and saturation. Diamonds are notorious for their fire and brilliancy. Rubies and emeralds are acknowledged for their intensity and beautiful overall color.

3. 

   Gain knowledge of the selected gemstones' origin. Certain stones are questionable due to augmentation or enhancements. Inquire about treatments done to the gemstone. These improvements include coating, heat treatment, diffusion, laser treatments, irradiation, colorless or infused color. Other than cutting and polishing, any method that improves the stone in any way varies its value. It guides the price, demand and availability, appearance and durability of the stone in question.

4. 

   Ask if the gemstone is natural or synthetic. With the use of technical instruments, characteristics of the gemstone are measured. A professional or certified gemologist tests the gemstone in a laboratory. She measures the refractive index, optical character of the gemstone, dispersion of light, the gemstone's reaction to ultraviolet light, and its selective absorption. More simply, she observes its color, luster or the quality and quantity of light reflected from its surface and the gemstone's density.

Tips & Warnings

• Consider the carat weight of the gemstone. Decide on the cut of the stone. Note the quality of the workmanship of cut and polished gemstones. Ask questions. Review the certificate of authenticity. Seek a certified gemologist appraiser or a certified gemologist before purchasing any gemstones of great value.

• Don't be rushed. Make certain the jeweler is certified. Look for an IGS (International Gem Society) certificate or other official recognition document.

Resources

• International Gem Society
• American Gem Society
• American Gemological Laboratories
• Gemological Institute of America