Imitations and Reconstruction 215
by creating " doublets" and "
triplets." The doublet is constructed with the table and crown of a
genuine stone, usually off-coloured, cemented to a pavilion made of a
paste having the approved colour, thus giving the valueless crown the
appearance of a fine stone. The softness of its pavilion usually
betrays the doublet. As a guard against this discovery the triplet was
invented. This is a real gem, usually pale or off-coloured, with a thin
layer of coloured glass at the girdle. The detection of this
combination usually requires the magnifying glass and specific gravity
tests; the glass usually betrays the deception, and if soaked in
alcohol, carbon bisulphide, or ether, the fraud usually separates.
Pearls are imitated by coating the inner surfaces of glass beads with a
preparation made from fish-scales.
Substitution
of other minerals for specific precious stones has not the shadow of
justification that sometimes softens the annoyance of receiving, or
being offered, " something just as good " in drugs, groceries, or dry
goods. The substitutes sometimes offered or proposed for diamonds
include white sapphires, zircon, quartz, and white topaz. Artifice is
frequently employed to heighten or change the colour of
