The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-02-07
F @ X

OF the material in the limitations re.
| suits In a peculiar striation when the>,
artificial stones are polished. and this il
| apparent, especially through a magnify
ing glass.
Imitation rubies are subject to in.
jury when exposed to extreme cold.
They have been known to crack open
in a single night, even when stored In
a safe.
The most pronounced difference to the
eye is the inferior degree of fire and
orllliance in the imitation ruby These
eHects are produced by the reflection.
refraction and dispersion of light by the
stone and its facets. Part Of the light
IS broken into the spectrum, or rain
now colors. The limitations are not
equal TO the natural stones in giving
GU; brilliant optical effects
The science of optics has in the last
year or so given much aid to Jew, l,gs
IN making tests that are said to be abb
solutely conclusive as TO the natur, Of
gem. The retroactive index. or lie.
power of bending light rays, is deter
mined as TO precious stones in tn, same
way as that of the spectacle lenses
which the opticians sell.
This retroactive index gives the Gina
as to the nature of a supposed gem
1t is possible for the laboratories. by m.
manipulation Of lead glass or other COM
pounds, to produce the same refrac..le
index as in the stone that is initiated
but in that case the specific pr,,.,y
OF one Will differ from that of the o.l,r
Consequently every imitation will differ
from the natural product as 10 one. or
the other of these two qualities.
The precious stone experts readily
Apply the tests for these qualities and
SO have a simple and sure means If
Distinguishing the real from the lm.,a-
ton gem.
Ihere are various other optical tests
'haF are certain 10 expose the false
gem one is found in the fact that
natural stones, being Of crystal furna.
tion' give double images Of objects seen
through them because Of what opticians
cal double refraction. In the cas-, #
colored stones the two images ar, Of
different colors.
ANY person may easily test sup.
posed precious stone for these double
images. The only real gems thar DO
not refract doubly are the semi-preg.uus
stones garnet and spinel.
Jewellers say that the statemeu.s Of
the chemists as 10 laboratory Gems
nave peen exaggerated in various ways
and as result dishonest dealers often
take advantage Of the situation such
dealers may try occasionally L. sell an
mutation for real gem, but NOR, COM
mon frauds are in making eXtrtv4Eant
claims for the limitations.
Rubies and sapphires are declared by
Vhe Jewellers to be the only gems thai
are really reproduced in the laoorato-
ries with the same chemical composition
as the natural stones Both ar, sons
OF the corundum group.
The first artificial rubies were made
by fusing the dust Of small and N
ferior rubies and the produD's We're
called reconstructed rub.,s They
brought from $50 to $50 a cara. and
were soon driven from the maraut 10y
the cheaper synthetic or scicu.. rl-
bies. These are made by m.A.n- ana
fusing certain chemicals which u.e NOT
costly, and the imitation gems are sold
by legitimate dealers for a sma. par.
of the prices of the old, reCors tac.ed
rubies. One fraud is in Sc.HA- ne
synthetic rubies at high prices, 'l.hI
them reconstructed and Representing
them as made up Of real, nature. rl'
bies.
Another fraud Is in selling a'Nh.."
white sapphires as synthetic diam nus
The jewellers say that no synth''. L''
monds have ever been made for q. mar
ket. Diamond dust has been m '' "'
enormous cost in experiments, ~
diamonds suitable for ornamcn.- nave
ever been made artiicialiy Tie ia.
mond dust made by a French 'AS.
would cost vastly more than MAI
dust from the diamond mines 81 W."
| Africa
| The dishonest dealer can get q MUG"
| higher price for the synthetic s'i'W'N
IL he can persuade his customer 'a'l "
is a diamond. Blue is the drsiAoe
color for sapphire, and therefor. FIT a.,
fetal white sapphlres are not Of '.'.
account when sold simply lor """'
they are,