The Japanese had started the production of cheaper cultured pearls in 1921 which however, led to an economic depression in Europe causing a drop in demand for natural pearls in the 1930's.
After the production of perfectly sperical cultured marine pearls was perfected by the Japanese, the production of pearls in other locations expanded.
For a cultured pearl, a spherical bead of mother-of-pearl is introduced into an oyster which builds up a thin layer of nacre around it.
Cultured pearls have a different lustre and color than a natural pearl.
Natural, cultured or fake?
Cultured pearls can be detected by X-rays or UV Fluorescence tests but there are other ways to tell the difference.
- If you can see a dark line in the drill hole (dividing the nacre from the irritant) the pearl is cultured.
- If the pearl looks perfectly round it is likely to be cultured or fake.
- Natural pearls feel rough when rubbed against the teeth, fake ones feel smooth.
- Hold the pearl in front of a stong light. If you see curved lines and stripes, the layers of nacre are thin and the pearl is cultured.
- Cultured pearls often have a fade greenish tint.
Fake pearls are either too heavy (inside filled with glass)or too light (inside is plastic)
In Japan Kokichi Mikimoto, using the Akoya oyster Pinctada fucata martensii, improved and perfected methods already known to the Chinese.
A bead of mother-of-pearl is carefully inserted into an oyster, which will then attempt to expel the irritant by coating it first in conchiolin and then layers of nacre.
Thick and high quality nacre will produce a beautifully irridescent and long-lasting pearl.