DIAMOND. 25 
melting of silver, it gradually dissipates and burns. 
Diamonds have been shown to consist principally of 
carbon or charcoal in a pure and crystallized state. 
The ancients, ignorant of the art of cutting dia- 
monds, were contented to set them in a native state ; 
and'for this purpose they preferred such stones as had 
naturally a crystallized form. The four large diamonds 
which ornament the clasp of the Imperial mantle of 
Charlemagne, and which are still preserved in Paris, 
are uncut stones of this description. The extreme 
hardness of the diamond baffled all attempts to polish it 
in such manner as to exhibit its peculiar beauty, until 
the year 14<56, when a young man of Bruges, whose 
name was Berquin, endeavoured to polish two diamonds 
by rubbing them against each other. Having suc- 
ceeded in this, he next constructed a wheel, on which, 
by means of diamond powder, he was enabled to cut 
and polish these gems in a manner beyond his greatest 
expectation. Since this period the art of polishing 
them has been greatly improved both by the Dutch and 
British jewellers. 
In the choosing and valuing of diamonds in a rough 
state, attention is paid to their colour, their being free 
from extraneous matter, and their shape. Those that 
are most perfect are crystalline, and resemble a drop 
of clear spring water, in the middle of which is to be 
perceived a strong light, that plays with great spirit on 
moving them about. When they have a yellowish or 
greenish tinge they are considered to be bad. Many 
diamonds have a kind of confused structure, whien 
lapidaries compare to knots formed in wood. These 
are rejected, from the impossibility of polishing them 
properly. 
Mr. Mawe remarks that diamonds, when rubbed 
together, have a peculiarly and scarcely to be described 
grating sound, which is one of their most remarkable 
characteristics. By this alone rough diamonds may be 
accurately and expeditiously distinguished from every 
other gem. 
VOL. i. c 
