sets."
Double brilliants are those cut in sixty-four facets, thirty-two upper
and thirty-two lower; and the sets of these met with in commerce are
called double sets.
The
Holland rose diamonds are cut in twenty-four upper facets, arranged so
as to have the form of a cupola, the lower part remaining flat and
smooth. "When this work is perfect the stone is said to be well
crowned. The rose diamonds having six, eight, or twelve facets are
called Antwerp rose. Those called " fiamminghi," or half brilliants,
have thirty-two upper facets, and a smooth surface underneath, the
lower part being wanting. To these the deficient part is frequently
added, being formed of common crystal equally facetted, and joined to
the diamond by means of mastic ; in this case it is called " doubled
diamond."
In working the diamond there are three operations, viz., cleavage, cleaning, and polishing.
The
weight of the finished diamond differs sensibly from that of the rough
stone, as in the cutting and other operations a considerable part is
lost.
Barbot calculates this diminution to be forty per cent, in diamonds of one carat, and fifty in the larger ones.
A
brilliant is considered perfect when it has a regular form, a very
clear colour, and is without spot or defect inside or outside. With
respect to the prices of these gems, we give here Barbot's table of
current prices at Paris in 1858 :
