There
is another material loss occurring in cutting or in the handling of
rough diamonds from a curious infirmity of some of these crystals. The
explosion of diamonds sometimes occurs, and the loss is the greater
because large stones are more liable to explode or fly into pieces than
small ones. This phenomenon is attributed to the heat of the hot
solder, or frictional heat of the revolving disk.
The Lapidaries
Early
handlers of the diamond were hardly more than polishers, striving to
produce an even, glistening surface, and satisfied to retain the
natural face of the stone, or to grind away some upper portion of the
crust. This clearly appears from the many old, half-polished stones
that have been found in treasuries of gems. A signal instance is shown
on the royal mantle of Charlemagne, still preserved in the French
National Collection. In the clasp of this robe are diamonds whose
natural octahedral faces have been simply polished. In ancient church
furnishings diamonds have been found with an upper table and four
polished borders, and the lower sides cut as four-sided prisms or
pyramids. Streeter quotes this inventory of the Duke of Anjou's jewels
exhibited in 1360 a.d. :
(1) a diamond of a shield shape, from a reliquary ; (2) two small
diamonds from the same reliquary, with three flat-cut, four-cornered
facets on both sides; (3) a small diamond in the form of a round mirror
; (4) a thick diamond with four facets; (5) a diamond in the form of a
lozenge; (6) an eight-sided, and (7) a six-sided plain diamond.1
We must allow, of course, for the mistakes and the ignorance of those
who may have catalogued rock crystals for diamonds, but granting that
some were diamonds, their existence shows what forms were then
prevalent and the real development of diamond cutting.
Previous to the success of de Berquem as a lapidary, there
were polishers and cutters in Paris and at Nuremburg, as has
been noted. A guild was organized in Paris in 1290 a.d., and
the table cutters joined in a guild with the stone engravers in
1 "Precious Stones and Gems," Streeter, 1880.
