The Roanoke times. [volume] (Roanoke, Va.) 1890-1895, 1892-08-19
BOGUS GEMS.
Countcrfeits OF Precious Stones and How
They Arc Made.

Countcrfeits OF Precious Stones and How
They Arc Made.
The finest imitation diamonds are
made out Of rock crystal" said n Wash
ngton dealer in precious stones to a
writer for the Star of that city. 1.-THE
basis of the most successful counter
feits Of all kinds of gems is q pure, very
dense, ana highly transparent sort of
glass, which is termed paste in the
Grade. For false diamonds this glass is
simply cut and polished in facets,
while for Initiating other stones, such
us rubies. emernlds, sapphires, ETC.,
metallic oxides are mixed with it.
I'm manufacturing glass for such pur-
poses the processes employed have to
be conducted with the utmost nicetv
For making even the best mirrors tho
necessary silica is obtained from
ordinary white quartz, while common
window panes are produced from sea
sand to large extent; but, in this
case, rock crystal is substituted, COM
posing about fifty per cent. of the in
gradients OF the paste. To it must be
added twenty-twop per cent. of carbonate
of soda and due proportions Of calcincd
boraX. snltpeter, and red lead All of
these things are reduced to the finest
powder, mixed. fused together by heat
in crucible and cooled slowly
THE density, transparency, and
beauty of the paste depend upon the
care taken in these processes. Thus
made, it is NIL ready to be cut ND into
diamonds and prepared for market. 1t
may be, however, that the manufac-
turcr desires to produce counter
felt gems OF other sorts. If so, he
has the means readily at hand.
Surprising that he wants rubics. he
fuses with paste very small quantity
OF peroxide of manganese and 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 crucf-
BILE by mixing with one thousand parts
OF the paste forty parts of glass of anti
mony and one part of Cassius purple.
For manufacturing other kinds of gems
there nrc methods equally simple. Of
course, none of these imitation precious
stones has the chemical constitution,
hardness, specific gravity, or optical
properties of real ones. Accordingly.
their falseness is readily perceived by
an expert. Inasmuch us the elements
of which various gems are composed
arc well known, synthetic chemistry
has attempted to reproduce them by
putting the ingredients together and
cffecting capitalization in the labora-
tory. In this way large masses of what
might be termed true ruby and sap
phire are turned out artificially. such
gem-lil1e material having some useful
ness for industrial purposes although
hacking 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 re-
produced by nrtifcc. The chemists
who have hitherto confined their attcn-
ton to taking things apart nrc begin
ming to learn how to put them together.
All the gems are very simple in their
composition, and the problem is merely
10 make their elements .crystallise
properly. In all such knowledge
eciencc has made 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 latter 10
pass through"