112 NATURAL HISTORY OF PRECIOUS STONES, &c.
commands
a far higher price in the market ; for the lustre of a brilliant
depends in great measure upon the judicious distribution and accurate
finish of the facets composing its sides.
De
Boot, who, assisting his imperial master, worked long and sedulously at
this art, has left many curious details of the process as carried on in
his times. He gives a figure of an ingenious contrivance invented by
himself for cutting several stones at once. It may be briefly
described as a horizontal, circular frame, perforated with sixteen
holes, which received as many handles, on whose ends the diamonds were
cemented.* These handles, by weights applied at top, kept the stones in
close contact with the wheel revolving below horizontally, which was a
mere rim of pewter equal in circumference ("three feet) to the frame
above, and provided with a border to keep the diamond-dust and oil with
which it was moistened from falling off. As may be supposed, from want
of motive power (the machine being driven by the foot bike a turner's
lathe), the operation was very slow : he mentions that it was only
necessary to unbed each stone once a week. But it must be borne in mind
no cutting of facets was as yet attempted : the wheel had only to
attack the large and simple planes of tables and of pyramids. He knows
nothing of the brutage or preliminary shaping of the stone,
but states that this pewter wheel was employed for cutting down the
Diamond as well as for polishing it. The diamond-powder was then
obtained by breaking up inferior atones with a large hammer : its value
was ten thalers per scruple. But in the next fifty years such rapid
progress had the art made that De Laet describes the hrutage, and the subse-
