Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1892-12-17
OUNTERFEITINC GEMS.

Glass the Basis of 1nitation---Geal Gem.
Produced ArtiiiciaIly.
THE finest imitation diamonds are
made out of rock crystal" said a Wash
ington dealer in precious stones. THE
basis of the most successful counter
feits Of all kinds of gems is 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 rub
les, emeralds, sapphires, etc, metallic
oxides are used with it.
'In manufacturing glass for such pur.
poses the processes employed have to
be conducted with the utmost nicely.
For making even the best mirrors the
necessary SILICA is obtained from or
binary white quartz, while common
window panes are produced from sea
sand to large extent; but, in this case,
rock crystal is substituted, composing
about 80 per cent. of the ingredients
OF the paste To it must be added %
per cent. of carbonate Of soda and due
proportions Of calcined borax, saltpetre
and red lead All these things are re-
duced to the finest powder, mixed,
fused together by heat in crucible
and cooled slowly.
''The density, transparency and beau
ty Of the plate depend upon the care
taken in these processes, Thus made,
1t is all ready to be cut up into dia-
monds and prepared for maket It
may be, however, that the manufacture
er desires to produce counterfeit gems
Of other sorts. If, so, he has the means
readily at hand. Surprising that he
small quantity of peroxide of manga
nese and a trace of CassiuS purple,
which will give the proper color. For
emeralds, he employees in like manner
oxide Of iron, and for sapphires oxide
of cobalt
Topaz is easily formed In the cruel
BILE by mixing with 1000 parts of paste
forty parts of glass of an1mony and
one part of Cassius purple. For manu-
featuring other kinds of gems there
are methods equally simple. OF course,
none of these imitation precious stones
have the chemical constitution, hard
ness specific gravity or optical proper
ties of real ones. Accordingly, their
falsencss is readily perceived by an
expert. Inasnuch rs the elements of
which various gems are composed are
well known, synthetic chemistry has
attempted TO produce them 10y put
tug the ingredients together and effect
ing crystalization in the laboratory. In
this way large masses of what might
be termed true rubies and sapphires
are turned out artihcialy, such gem
like material having some usefulness
for industrial purposes, although lack
ing the brilliancy of natures products
For my own part | am confident
that sooner or later some, If not all,
of the stones deemed precious will be
reproduced by artifice. The chemists
who have hitherto confined their atten-
ton to taking things apart are begin
ming to learn how to put them together.
All the gems are very simple in compo-
sition and the problem is merely to
make their elements crystalline proper
". In all such knowledge science has
made but little progress as vet, We
do not even know for what reason one
substance 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 letter to pass
through"