The treatment of the gems has existed for several centuries. It is a question of subjecting a stone to a process to improve its aspect (purity, color or durability).
More and more stones are treated nowadays.
Some of these treatments are regarded as ancestral concise practices (like the oiling of emeralds) and thus are more or less tolerated.
The person who wishes to acquire a stone which was treated must be informed about it by the affixing of the mention “treated”.
Except in a minority of cases :
→ Extract of the french Decree N °2002-65 of January 14th, 2002 (available while clicking here) text in french
« The affixing of the mention” treated “or the indication of the treatment is not compulsory for the gemmeous stones, fine organic matters, pearls and pearls of culture having undergone the following traditional concise practices:
- an impregnation by a fluid colourless substance;
- a heat treatment, providing the possible residues of heating on the surface do not cause rupture of reflection visible with the magnifying glass of an enlargement of 10 times;
- a bleaching without addition of products dyes or varnish. »
- Surface coating
- Impregnation and filling
- Hight Pression Hight Temperatur (HPHT)
Certain treatments can be very difficult to detect. We thus recommend to buy your stones with merchants of confidence, with, if possible, a certificate issued by an independent laboratory, especially when it is an important investment.