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Destructive Gemstone Tests: Acid Testing

Acid testing is a destructive procedure gemologists can use to determine if some pieces are real or fake. Learn how to perform this test safely.

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HomeLearning CenterGemologyGemstone Testing and IdentificationDestructive Gemstone Tests: Acid Testing
By Donald Clark, CSM IMG

Organic Gem Materials

Natural coral, shell, and pearl are carbonates. Since they release a protein smell from hot point testing, you can’t use that test to distinguish them from plastic imitations. However, you can identify them by observing their reaction to acid.

Warnings

This is a potentially dangerous procedure for both stone and tester. Exercise great care. Keep in mind that acid testing is a destructive test that should only be conducted as a last resort.

Always Add Acid To Water

AAA – Always Add Acid to water! Never the other way around. If you pour water in acid, it will boil and splash out of the container. The acid will burn metal, wood, skin, etc. Memorize the AAA rule.

Pearl Warning

Since there are nondestructive ways to separate natural pearls from their imitations, acid testing isn’t recommended for pearls.

Necklace Alert

When acid testing a strand of beads, make sure you don’t get any fluid on the cord. The acids used for identification will damage cords.

Do Not Use Full-Strength Hydrochloric Acid

Full-strength hydrochloric or muriatic acid isn’t recommended for gem testing. Diluting full-strength acids on…

Donald Clark, CSM IMG

The late Donald Clark, CSM founded the International Gem Society in 1998. Donald started in the gem and jewelry industry in 1976. He received his formal gemology training from the Gemological Institute of America (GIA) and the American Society of Gemcutters (ASG). The letters “CSM” after his name stood for Certified Supreme Master Gemcutter, a designation of Wykoff’s ASG which has often been referred to as the doctorate of gem cutting. The American Society of Gemcutters only had 54 people reach this level. Along with dozens of articles for leading trade magazines, Donald authored the book “Modern Faceting, the Easy Way.”

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