Step 3: Practical Gemology

Lesson 22

In some cases, a hot point test will not distinguish plastic simulants or imitations from natural gems. Some plastics release a protein smell when hot point tested, just like their natural counterparts. Natural coral, shell, and pearl release a protein smell. These organic gem materials are carbonates, just like malachite and rhodochrosite. You can make a positive identification of these gem specimens through acid testing, examining how they react to acid.

Acid Testing Warnings

This is a potentially dangerous procedure for both the tester and the stone. Exercise great care.

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 is not 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