214 A Book of Precious Stones
Both
the genuine and artificial ruby are unaffected, while all imitations
made of paste, as imitation ruby, sapphire, emerald, etc., are quickly
attacked.
To
M. Antony Jacques, a jeweller of Grenoble, France, is accredited the
discovery of a new method of detecting counterfeit emeralds and
garnets, a method that is simple and that can be applied by any person.
Through two coloured glasses, placed across and upon one another, one
blue and the other yellow, the stone in question is examined, the stone
being placed directly against an electric lamp. The genuine emerald
will appear to be of a violet colour, no matter whether it is a "
scientific," a " reconstructed " gem, or an ordinary green doublet. The
most convincing imitation will appear unchanged and the deception thus
easily demonstrated. A genuine garnet similarly placed upon an
electric lamp and looked at through pale-green glass will appear
decolourised, while a counterfeit will remain a garnet colour. The
author's experiments have demonstrated the efficiency and reliability
of these tests.
Besides
the complete imitation of gems there are partial sophistications in
which considerable ingenuity and constructive ability are displayed
