Pearls have been imitated for centuries. Most pearl imitations are made by first producing a spherical glass or mother-of-pearl bead. The bead is then coated by a substance called pearl essence” which is made by mixing guanine (extracted from fish scales) with glue and a colouring agent. After a few layers of “essence” have been applied, the bead is polished and dipped in a chemical which hardens and protects the surface from chipping and discolouring.
Imitation pearls are normally sold under specific brand names such as “Majorica pearls”.
- A famous test is done by gently rubbing the pearl on your front teeth – if it feels gritty, it is a cultured pearl; if it feels like plastic on your teeth, it is an imitation. This is not conclusive as some imitations are produced with a gritty surface.
- Through a jeweller’s loupe the drill hole of a cultured pearl shows the thin, often dark layer of conchiolin that separates the bead nucleus from the nacre. The edge of the drill hole is sharp and well-defined. The presence of blemishes and the specific orient of cultured pearls are diagnostic.
- On the other hand, the drill holes in pearl imitations show the ragged edges of the coating and often no separation between the glass nucleus and coating can be seen. The drill hole of a cultured pearl is normally smooth and the thin layer of nacre that covers the bead can be seen (left). On the right, the ragged edges of the drill hole in the imitation bead is obvious.
- The surface of an imitation pearls is normally smooth and without blemishes.
- Imitation pearls are not as hard as cultured pearls. They also feel warm on the lips compared to the cold feel of cultured pearls.
- Pressing a needle on the surface of a fake pearl will leave a small hole while a cultured pearl will show no needle mark.
Visit Prins and Prins for a grading and valuation on your pearls.