which
the light rays have power to play; other stones, such as the opal,
turquoise and the like, are cut or ground in flat, dome-shaped, or
other form, and then merely polished. It frequently happens that only a
small portion of even a large stone is of supreme value or purity, the
cutter often retaining as his perquisite the smaller pieces and waste.
These, if too small for setting, are ground into powder and used to cut
and polish other stones.
Broadly
speaking, the greatest claim which a stone can possess in order to be
classed as precious is its rarity. To this may be added public opinion,
which is led for better or worse by the fashion of the moment. For if
the comparatively common amethyst should chance to be made
extraordinarily conspicuous by some society leader, it would at once
step from its humbler position as semiprecious, and rise to the nobler
classification of a truly precious stone, by reason of the demand
created for it, which would, in all probability, absorb the available
stock to rarity ; and this despite the more entrancing beauty of the
now rarer stones.
The
study of this section of mineralogy is one of intense interest, and by
understanding the nature, environment, chemical composition and the
properties of the stones, possibility of fraud is altogether precluded,
and there is induced in the mind—even of those with whom the study of
precious stones has no part commercially—an intelligent interest in
the sight or association of what might otherwise excite no more than a
mere glance of admiration or curiosity. There is scarcely any form of
matter, be it liquid, solid, or gaseous, but has
