The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1892-12-25
IMITATION GEMS.
How Many Kinds OF Prec;ous
Stones Arc Countorfoited.
Rock Crystal Plays m Important Part ip
tho Manufacture OF Artificial jew
eis-Ono Result OF Progress
In Chcmistry.

The finest imitation diamonds are
made out of rock crystal" said n Wash.
ington dealer in precious stones to a
Star man recently. "The basis OF the
most successful countcrfcits of all kinds
OF gems is n pure, very dense and highly
transparent sort of glass, which is
termed paste in the trade. For false
diamonds this glass is simply cut and
polished in facets, while for Initiating
other stones, such as rubies, cmeralds
sapphircs, etc, metallic oxides are
mixed with it.
I'm manufacturing glass for such pur
poses the processes employed have tc
be conducted with the utmost nicetv
For making even the best mirrors, the
necessary silica is obtained from orfii.
nary white quartz. while common win
dow pancs arc produced from sea sand
to large extent; but, in this case. rock
crystal is substituted, composing about
fifty per cent. of the ingredients of the
paste. To this must be added twenty
two per cent. of carbonate OF soda and
due proportions of calciucd boraX. salt
peter and red lead. All of these things
are reduced to the finest powder, mixed.
fused together by heat in n crucible and
cooled slowly.
Tho density, transparency and
beauty of the plate depend upon the
care taken in these processes. Thus
made, it is all ready to be cut up into
diamonds and prepared for market. II
may be, however, that the manufac-
turcr desires to produce counterfeit
gems of other sorts. If so, he has the
means readily at hand. Surprising that
he wants rubies, he fuses with paste n
small quantity of peroxide of manganese
and trace of Cassius purple, which
will give the proper color. For cmer-
aids, he employs in like manner oxide
of iron and for sapphircs oxide of CO.
bait.
Topaz is easily formed in the cruel
BILE by mixing with one thousand parts
of paste forty parts of glass of anti
mouy and one part of Cassius purple.
| For manufacturing other kinds of gems
there are methods equally simple. Of
course, none of these imitation precious
stones has the chemical constitution,
hardness, specific gravity or optical prop
critics of real ones. Accordingly their
falscness is readily perceived by an en-
pert. Inasmuch as the elements of
which various gems are composed are
well known, synthetic chemistry has
attempted to reproduce them by putting
the ingredients together and cffccting
disqualification in the laboratory. In
this way large masses of what might be
termed true ruby and sapphire are
turned out artlfcinlly, such gcm-lille
material having some usefulness for in
dustrial purposes although lacking the
brilliancy of natures products.
For my own part, I am confident
that sooner or later some, if not all, of
the stones deemed precious will be re.
| produced by artifice. The chemists who
have hitherto confined their attention
to taking things apart arc beginning to
learn how to put them together. All
the gems are very simple in compost
ton and the problem is merely to make
their elements crystalline properly. In
all such knowledge science has made
but little progress as yet. We do not
even know for what reason one sub
stance is transparent while another is
opaque; though presumably there is
some relation between the arrangement
Of the molecules in the transparent
body and the length of the light waves,
which, in the case of the transparent
body, permits the latter to pass
through"