ing
in a great many respects, is generally effected by giving the proper
shape to a morsel of strass; removing from the upper portion of it a
certain thickness, and replacing this by hard stone in such a way as to
complete exactly the strass stone, then mounting the whole in a setting
that completely conceals the line of junction of the two stones.
Doublets
are of two kinds: in both the under part is strass, but in one the
upper part is a plate of the real stone; in the other, it is simply
hard stone, generally quartz, and of no value.
The
invention of this process has been attributed to a modern jeweller of
Paris, named Bourguignon; but in reality it can be traced as far back
as the fifteenth century.
A
complete description of the mode of manufacturing doublets is given by
Cardan, who has even preserved for us the name of the inventor:—
"A fraud of a very bad character, and one very
difficult to find out, was employed by Zocolino------.
This
venerable personage used to take a thin flake of real precious stone,
such as carbuncle, emerald, &c, when he wished to imitate the
carbuncle or emerald, choosing such pieces as had but little colour,
and were consequently very cheap. Underneath he placed a piece of
crystal sufficiently thick, and united the two parts by means of a
transparent glue, in which he incorporated a colouring matter
