One way to identify antique pearls is by the type of pearl being presented. Jewelry makers predominantly used natural pearls up until the 1920s, and then they began to use cultured pearls during the Jazz Age. The only true way to identify if a vintage pearl is a natural pearl or a cultured pearl is with an x-ray examination. To identify antique pearls from the Renaissance, look for “baroque” pearls, or pearls shaped irregularly, which were popular at the time.
To identify antique pearls at home, use a 10x loupe and a flashlight to inspect the thread hole of a pearl. Natural pearls have layers similar to onion skin, while cultured pearls lack layers in the large centers of the beads. Another method to identify genuine antique pearls is by using a fiber optic light probe. Some appraisers feel the pearls with their teeth to distinguish the type of surface of the pearl. Natural antique pearls feel gritty, while plastic imitation pearls feel slippery.
When identifying and appraising antique pearls, rounder pearls have more value, as do white pearls and pink pearls. Creamy pearls have less value. To best preserve antique pearls, do not use an abrasive cleaner. A simple solution of soap and warm water is best for preserving pearls.