NO VALID DISTINCTION BETWEEN PRECIOUS AND SEMIPRECIOUS STONES.
United States Geological Survey -is often asked to make a distinction
between precious and semiprecious stones, and especially to state the
class in which some particular mineral belongs. To the popular mind the
diamond, rubj', sapphire, and emerald are the true precious stones: all
others are semiprecious. The popular mind, however, is not consistent
from time to time; the fickleness of fashion may readily change the
standing of gems; and demand and supply, popular taste, and price may
affect the rank of a precious stone.
stones are desired for personal adornment because of their rarity,
their cost, and especially their beauty, and these items probably
determine as much as any other the classification of gem stones. But
can agreement ever be reached as to what are the most beautiful of all
gem stones? The opinion and taste of the wearer, of the jeweler, and of
the scientist all deserve consideration, but the three can probably not
reach a satisfactory agreement.
short, no criteria of subdivision between precious and semiprecious
stones can be offered on which all gem stones can be classified. All
stones which are suitable for personal adornment and which please the
wearer may be called precious stones. Jasper is as much a precious
stone as diamond. The schemes of classification of gem stones into
precious and semiprecious are almost as numerous as the books written
on the subject, but not even all the authors can retain their
classification throughout. One author, in his table of contents,
divides gem stones into (a) precious stones (diamond, corundum, and beryl) ; (b) semiprecious stones (topaz, spinel, garnet, etc.); (c) ornamental stones (fluor, lapis lazuli, sodalite, etc.); and (d) organic
products (pearl, coral, amber) ; yet, in his text, he says: "Once
contemptuously styled common garnet, andradite suddenly sprang into the
rank of precious stones."
The properties that give minerals value as gem stones are color,
luster, transparency, hardness, and rarity. The first three are
sometimes grouped together under the head of beauty. It has been said
that a mineral must possess at least a majority of these properties in
order to be ranked as a precious as distinguished from a semiprecious
stone. An attempt to apply the test will show the futility of any such
subdivision. The application of such a subdivision would also
tables in this chapter giving statistics of the values of the gems and
precious stones produced in 1010 were compiled hy Miss Blanche H.