Sorry, Pearl Dream.. I must be stupid, I don't know how to use this code. I have created an account, but Pearlasone has not registered it (?).
Today, I have carved a sample of irregular pearl, bought in India. Surprise : under a very thin nacre layer, I have found a strange nucleus, which appears to be an over irregular pearl, same shape than the original, but coated by an terrible dirty yellow varnish... Maybe i'll find a shoe, sometime !
Well, reading a good paper about maeshori techniques, it's seems that a most part of pearls are treated.
I am surprised to see such treatements, with magnesium salts and over, and above all with optical brighteners, to be tolerated... It would not be with gem stones.