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GEMS AND PRECIOUS STONES.1
By Waldemar T. Schaller.
NO VALID DISTINCTION BETWEEN PRECIOUS AND SEMIPRECIOUS STONES.
The 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.
Gem 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.
In 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
1The tables in this chapter giving statistics of the values of the gems and precious stones produced in 1010 were compiled hy Miss Blanche H. Stoddard.
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