Gem Chart - Jewelry Diamond, Gem, Watch Appraisals by GIA Graduate Gemologist

How to Buy a Diamond

This GIA video takes you through the process of grading a diamond and ultimately learning what adds value.

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	Gem Information

Gems are naturally occurring materials that are beautiful, durable, and rare. There are approximately 250 different known Gems available to consumers. These all have different characteristics and qualities. They all need to be treated differently. The following Gem Chart explains the basic care and cleaning for the most common gems available in the marketplace. For specific instructions see the How To Clean Your Fine Jewelry page

In order to communicate the qualities and characteristics of gems, a descriptive language and grading system has been developed. These include standard terminologies which define Color, Cut, Clarity and Carat Weight. (The 4 C’s) The terms used to describe a Diamond is slightly different than the terms used to define a Colored Gem, but the end result is a comprehensive and standardized description of each individual Gem.

However, as you are shopping for a gem, remember that your own perception of its beauty is the most important factor to consider.

If you wish to learn more about buying gemstones and diamonds, explore the links below

Gem Chart

Alexandrite	Generally stable to light, heat & chemicals. Do not Steam Clean. Ultrasonic OK, with care (jewelers only).	Jade (Jadeite & Nephrite)	Often polished with wax finish. Avoid high heat, solvents, acids & strong light. Soak very briefly in ammonia then brush and rinse.
Amber	Easily damaged by heat, pressure, and chemicals. Wipe or soak in warm soapy water. Do not Ultrasonic or Steam Clean.	Kunzite (Spodumene)	Do not Ultrasonic or Steam Clean. Heat & strong light can change color. Soak in ammonia, brush & rinse. Avoid hydrofluoric acid.
Amethyst (Quartz)	Avoid strong heat & abrupt temperature changes. Ultrasonic or Steam Cleaning should be done with care not to "thermal shock" the stone. Soak in ammonia & brush	Lapis Lazuli	Do not Ultrasonic or Steam Clean. Do not Ultrasonic or Steam Clean. Often dyed. Avoid heat, solvents, acids, strong abrasive detergents. Clean gently with warm soapy water.
Andalusite	Ultrasonic OK. Do not Steam Clean.	Malachite	Do not Ultrasonic or Steam Clean. Avoid heat, solvents and acids. Clean gently with warm soapy water.
Apatite	Heat & strong light can cause color to change or fade. Do not Ultrasonic or Steam Clean.	Opal	Very delicate & heat sensitive. Do not Ultrasonic or Steam Clean. Avoid all solvents, acids, heat & abrasive substances. Brush with warm soapy water; brush accent gems.
Aquamarine (Beryl)	Do not Steam Clean. Ultrasonic with caution: jewelers should check for dangerous inclusions. Acids can cause damage, especially hydrofluoric acid. Clean using ammonia, brush & rinse. Brush accent gems with warm, soapy water.	Pearls	Organic; avoid chemicals, hair spray, perfume, perspiration. Very soft. Do not Ultrasonic or Steam Clean. Wipe with soft, damp cloth after wearing. Do not store in safe deposit box for long periods. Prefers light.
Beryl	Generally stable. Do not Steam Clean. Ultrasonic cleaning is OK.	Peridot	May fracture if heat-shocked. Do not Ultrasonic. Steam Clean with care. Damaged by acids. Soak in ammonia & brush clean.
Cat's Eye (Chrysoberyl)	Strong heat (jeweler’s torch) may destroy color. Ultrasonic or Steam Cleaning best done carefully, by a jeweler. Clean using ammonia & warm soapy water, brush.	Quartz	Avoid strong heat & abrupt temperature changes. Ultrasonic or Steam Cleaning should be done with care not to "thermal shock" the stone. Soak in ammonia & brush.
Citrine (Quartz)	Avoid strong heat & abrupt temperature changes. Ultrasonic or Steam Cleaning should be done with care not to "thermal shock" the stone. Soak in ammonia & brush.	Ruby & Sapphire (Corundum)	Ultrasonic or Steam Cleaning is generally safe. Clean with hot, soapy water & ammonia just like Diamond. Caution: Gems with glass-filled cavities could be damaged.
Coral	Organic; avoid chemicals, hair spray, perfume, perspiration. Very soft. Do not Ultrasonic or Steam Clean. Wipe with soft, damp cloth after wearing. Do not store in safe deposit box for long periods. Brush accent stones & clean with warm soapy water.	Spinel	Steam Cleaning OK, but avoid thermal shock. Ultrasonic Cleaning OK, with care. Jeweler’s torch may fade light colors. Clean using ammonia & warm soapy water, brush. Thermal shock can cause gem to fracture. Damaged by hydrofluoric & hydrochloric (Chlorine - Bleach) acids.
Diamond	Untreated diamonds are OK for Ultrasonic or Steam Cleaning. Daily cleaning soak in hot water, ammonia, brush & rinse. Fracture-filled diamonds must be treated with care. A Jeweler's torch can remove these treatments. Let him know if your diamond is Fracture-filled!	Tanzanite (Zoisite)	Do not Ultrasonic or Steam Clean. The gem can fracture, if thermal shocked. Soak in warm soapy water, ammonia, brush & rinse.
Diopside	Do not Ultrasonic or Steam Clean. Do not expose to hydrofluoric acid. Very heat-sensitive. Clean using ammonia & warm soapy water, brush.	Topaz	Do not Ultrasonic or Steam Clean. The gem can fracture, if thermal shocked. Soak in warm soapy water, ammonia, brush & rinse.
Emerald (Beryl)	Use extreme care. Usually enhanced & treated with oils or resins that can be removed with cleaning. (Fracture-fillings can be restored.) Do not Ultrasonic or Steam Clean. Clean using cool soapy water, brush & cold rinse.	Turquoise	Do not Ultrasonic or Steam Clean. Attacked by acids. Cosmetics or perspiration may cause stone discoloration. Many are dyed or "stabilized" with resins. Brush with warm soapy water, rinse & dry.
Garnet	Steam Cleaning OK, but avoid thermal shock. Ultrasonic Cleaning OK, with care. Avoid hydrofluoric acid & high heat (Jeweler’s torch). Clean using ammonia & warm soapy water, brush & rinse.	Zircon	Do not Steam Clean. Ultrasonic Cleaning OK. High heat or strong light can cause a change color. Easily abraded (scratched) —handle with care. Clean using ammonia & warm soapy water, brush & rinse.
Iolite	Ultrasonic or Steam Cleaning OK. Avoid thermal shock. Acids can damage. Clean using ammonia & warm soapy water, brush & rinse.	*Caution*:	Please use care in cleaning your jewelry. Clean in a small bowl, and check carefully for loose or dislodged stones.


	An independent appraiser can help you determine if you are paying the right price for the gem you have selected, but do not fall into the trap of purchasing "words on paper", instead choose the gem that speaks to your soul!


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