Gem-Stones and Their Distinctive CharactersSmith, George Frederick Herbert
Science
Gem-Stones and Their Distinctive Characters
Smith, George Frederick Herbert
Precious stones
The varieties most adapted to jewellery are the fiery-red pyrope and
the crimson and columbine-red almandine; the closer they approach the
ruddy hue of ruby the better they are appreciated. Hessonite was at one
time in some demand, but it inclines too much to the yellowish shade
of red and possesses too little perfection of transparency to accord
with the taste of the present day. Demantoid provides beautiful, pale
and dark emerald-green stones, of brilliant lustre and high dispersion,
which are admirably adapted for use in pendants or necklaces; on
account of their comparative softness it would be unwise to risk them
in rings. In many stones the colour takes a yellowish shade, which
is less in demand. Uvarovite also occurs in attractive emerald-green
stones, but unfortunately none as yet have been found large enough for
cutting. A few truly magnificent spessartites are known—one, a splendid
example, weighing 6¾ carats, being in the possession of Sir Arthur
Church; but the species is far too seldom transparent to come into
general use. The price varies per carat from 2s. for common garnet to
10s. for stones most akin to ruby in colour, and exceptional demantoids
may realize even as much as £10 a carat. The old style of cutting was
almost invariably rounded or _en cabochon_, but at the present day the
brilliant-cut front and the step-cut back is most commonly adopted.
The several varieties will now be considered in detail.
(_a_) HESSONITE
(_Grossular_, _Cinnamon-Stone_, _Hyacinth_, _Jacinth_)
This variety, strictly a calcium-aluminium garnet corresponding to
the formula Ca_{3}Al_{2}(SiO_{4})_{3}, but generally containing some
ferric oxide and therefore tending towards andradite, is called by
several different names. In science it is usually termed grossular, a
word derived from _grossularia_, the botanical name for gooseberry, in
allusion to the colour and appearance of many crystals, or hessonite,
and less correctly essonite, words derived from the Greek ἥσσων
in reference to the inferior hardness of these stones as compared
with zircon of similar colour; in jewellery it is better known as
cinnamon-stone, if a golden-yellow in colour, or hyacinth or jacinth.
The last word, which is indiscriminately used for hessonite and yellow
zircon, but should more properly be applied to the latter, is derived
from an old Indian word (cf. p. 229); jewellers, however, retain it for
the garnet.
Public-domain text, read in full here on John Shaqi.
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