, 1886-04-21
pggcaIprIoN 81 PRECIOUS STONES


The Principal Transparent Gsms-How
Values are Ansctsd-Beauty.
The principal transparent gems are the
diamond, white sapphire, colorless topaz
and crystal. colorless or only slightly
tinged with yellow or brown, as in the
African diamonds and in smoky quartz,
or shot with changeable CLEANS Of light,
as in the moonstone, opal and cat's-eye-
The yellow sapphire and topaz are Of
positive yellow, not mere tints; the
sapphire is blue; the ruby. pink; topaz,
garnet and hyacinth are red; the emerald,
beryl, modern crysolite, aquamarine are
green Of various tints; the amethyst is
purple.
The translucent stones are nearly all Of
them varieties Of quartz; chalcedony,
which is white; ~chyrsoprase, green; sard,
varying from yellow to brown; a blood
red variety having the specific name OF
carnelian 1.-THE flesh tinted), although, by
a paraphrase of this name, carnellan
(the horny textured), the specific work
ing quality Of chalcedony, carnelian and
sardonyx is indicated, and the stones
themselves often spoken of, descriptive
words being added, as white for chalce-
dony; red, yellow or brown for s~ardonyr;
the agate, a ~variegated stone, usually
brown and white, and often with very
beautiful figures; the ony1, a blue and
white or black and white stone in layers,
often almost Opaque; the sardonyx, ared
and white stone in layers.
The Opaque stones are hematite or
bloodstone proper, a compact oxide Of
iron, sometimes true hematite, but more
usually specular ore. which, II magnetic,
as it often is, is the bar-lashi OF the gyp-
sizes. and probably also the -ligure" of
the breast-plate of Israel's high priest;
heliotrope, frequently called bloodstone,
a green stone with red spots; turquoise
and lapis lazuli, which are blue; calca-
huiti, the green Mexican turquoise;
porphyIy, which is either green or red;
malachite, which is green, beautifully
veined; and jasper, an Opaque stone
colored in greens, browns, reds, yellows
and white, sometimes self colored some
times very beautifully mottled,
Purity Of color and freedom from flaws
affects the value Of all stones, and per
lection of shape has also great influence.
For instance, the emerald, beryl and
n4hhnlhi ~ CntiiliCdii1 nearly hllhts
and similarly crystallized, yet of vastly
different values, on account Of their
colors and textures. The ton or so Of
beryl in the natural history rooms would
be Of far less value than the fve-ounce
Hope emerald, except to destroy as a
source of g~lucina.
To enhance the beauty Of gems they
are cut and polished substantially in one
Of three ways, either into facets, as is
usually done with transparent stones, so
as to give as many retroactive and re-
Elective surfaces as possible, or en-
cabochon, where either the natural sur
faces are polished, or the stone is rounded
up, like carbuncles, opals, cats eyes and
moonstones, or if opaque or translucent
stones, into shapes for rings, brooches
and the like; and these last are frequently
engraved in relief or intagio, or in the
round, to wear as ornaments or use as
seals.
This cutting, polishing and engraving
is a work Of great expense, and takes
away much Of the substance of the gem;
in the transparent ~brilliant-cut gems
usually reducing their weight one-half,
and increasing their value to q still
greater degree roughly speaking, more
than trebling the value per carat, while
it halves the number of carats by which
to multiply this value. Boston Budget.