The Portland daily press., 1893-01-25
Counterfeit Gems.
Washington Star.1

1.-THE finest imitation diamonds are
made out of rock crystal said Wash
ington dealer in precious stones. 'sThe
basis of the most successful counterfeits
of all kinds of gems is a 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 imi-
tating other stones, such as rubies, en-
erals, sapphires, etc., metallic oxides are
mixed with it.
''In manufacturing glass for such pur-
pc ,es the processes employed have to be
conducted with the utmost nicely. For
making even the best mirrors the neces-
sary silica is obtained from white quartz
while common window panes are pro-
duced from sea sand to large extent;
but in this case rock crystals substituted,
composing about50 per cent. of the ingre-
dients of the paste. To it must be added
% per cent. Of carbonate of soda and due
proportions of calcined borax, saltpeter
and red lead. All of these things are re-
duced to the finest powder, mixed, fused
together by heat in crucible and cooled
slowly.
1.-THE density, transparency and beauty
of t e plate depend upon the care taken
ready to be cut ~ into diam onds and
prepared for market. It may be, how
ever, that the manufacturer desires to
produce counterfeit gems of other Sorts
If so, he has the means readily at hand.
Supposing that he wants rubies, he fuses
with paste small quantity of peroxide
of manganese and and a trace of Cassius
purple, which will give the proper color.
For emeralds he employs in like manner
oxide of iron, and for sapphires oxide of
COBALT.
TOPAZ is easily formed in the crucible
by mixing with 1000 parts of paste 40
parts of glass of anthony and one part
of Cassius purple. For manufacturing
other kinds of gems there are methods
equa ly simple. Of course none of these
imitation precious stones has the chemi-
cal constitution, hardness, specific gravity
or optical properties of real ones. Ac-
cordingly, their falseness is readily per-
ceived by an expert. Inasmuch as the
elements of which various gems are COM
posed are well known, synthetic chem
istry has attempted to reproduce them
by putting the ingredients together and
effecting crystalization in the laboratory.
In this way large masses of lwhat might
be termed true ruby and sapphire are
turned out artifcially, such gem-like
material having some usefulness for in
dustrial purposes although lacking the
brilliancy of natures products.
ssFor my own part, am confident that
sooner or later some, if not all, of The
stones deemed precious will be repro
duced by artifice. The chemists who
have hitherto confined their attention to
learn how to put them together. All the
gems are very simple in composition and
the problem is merely to make their ele-
ments crystalline properly. In all such
knowledge science has made but little
progress as yet. We do not even know
for what reason one substance is trans
parent while another is Opaque, though
presumably there is some relation be-
tween 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