in
harmony with the stone that he meant to imitate—brilliant red for
carbuncle, green for emerald, &c. He concealed the line of junction
of the two parts by means of the setting; and to avoid giving rise to
suspicion, he set them in gold, which was not allowed except in the
case of real precious stones.
"In
this way this magnificent workman deceived everybody, even the
lapidaries. However, the fraud was at last discovered, and Zocolino
took refuge in flight.
"
It appears that this personage had a peculiar disposition for fraud,
for he turned his attention afterwards to the fabrication of
counterfeit money; and ended by being condemned to death."
An
examination of the objects adorned with precious stones, that have been
executed in the middle ages, shows that the process described by Cardan
was not unfrequently employed.
FALSE PRECIOUS STONES OF THE ARTIFICIAL KIND.
The basis of all false stones of this kind is glass.
A
fixed alkali (soda or potash) and silica heated to a red heat will
combine and produce glass. Alumina, lime, magnesia, &c, may enter
into the combination with the silica; but the result in both
