Step 3: Practical Gemology

Lesson 22

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.


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

AAAAlways 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…