The light green and blue green beryls are correctly called aquamarines, the pale sky-blue beryls should be named simply blue beryl. Yellow beryl may be called golden beryl, or it may be called "heliodor," a name that was devised for the fine yellow beryl of Madagascar. Beautiful pink beryl from Madagascar has been called "morganite," a name that deserves to live in order to commemorate the great interest taken by J. Pierpont Morgan in collecting and conserving for future generations many of the gems in the American Museum of Natural History in New York.
Zircon. We now come to a number of minerals slightly less hard than beryl, but harder than quartz, and zircon is perhaps as hard as any of these, so it will be considered next. Red zircon, which is rare, is properly called "hyacinth." Many Hessonite garnets (cinnamon stones) are incorrectly called hyacinths, however. The true hyacinth has more snap and fire owing to its adamantine surface luster and high dispersive power, as well as to its high refractive index. A true hyacinth is a beautiful stone. Golden yellow zircons are correctly called "jacinths." Artificially whitened zircons (the color of which has been removed by heating) are known as "jargoons" or sometimes as "Matura diamonds." All other colors in zircon should be named simply zircon, with a color adjective to indicate the particular color as, "brown zircon," etc.
Tourmaline. Tourmaline furnishes gems of many different colors. These are all usually called simply tourmaline, with a color adjective to specify the particular color, as, for example, the "pink tourmaline" of California. Red tourmaline is, however, sometimes called "rubellite," and white tourmaline has been called "achroite." The latter material is seldom cut, and hence the name is seldom seen or used.
Garnet. We may next consider the garnets, as most of them are somewhat harder than quartz. As was said in [Lesson XVIII.] in our study of mineral species, there are several types of garnets, characterized by similarity of chemical composition, or at least by analogy of composition, but, having specific differences of property. The names used by jewelers for the several types of garnets ought to be a fairly true indication as to the type in hand in a particular case. At present there is considerable confusion in the naming of garnets. The most common practice is to call all garnets of a purplish-red color "almandines." As many such garnets belong to the mineral species almandite garnet, there is little objection to the continuance of this practice. The somewhat less dense, and less hard blood red garnets are properly called "pyrope garnets" (literally "fire" garnets). Many of the Arizona garnets belong in this division. The term "Arizona rubies" should not be used. As was said under ruby, nothing but red corundum should receive that title. Similarly the pyrope garnet of the diamond mines of South Africa is incorrectly called "Cape ruby." Pyrope and almandite garnet tend to merge in composition and in properties, and the beautiful "Rhodolite" garnets of Macon County, North Carolina, are between the two varieties in composition, in color, and in other properties.
Hessonite garnet furnishes yellowish-red and brownish-red stones, which are sometimes also called "cinnamon stones." They are also frequently and incorrectly called jacinth or hyacinth, terms which, as we have seen, should be reserved for yellow and red zircon, respectively.
Andradite garnet furnishes brilliant green stones, which have been incorrectly named "Olivines" by the trade. The name is unfortunate as it is identical with the true name of the mineral which gives us peridot. The name does not even suggest the color of these garnets correctly, as they are seldom olive green in shade. As the scarcity of fine specimens and their great beauty make a fairly high price necessary, the public would hardly pay it for anything that was called "garnet," as garnets are regarded as common and cheap. Perhaps the adoption of the name "Demantoid" might relieve the situation. The stones are frequently referred to as "demantoid garnets" on account of their diamond-like luster and dispersion. The use of "demantoid" alone, if a noun may be made from the adjective, would avoid both the confusion with the mineral olivine, and the cheapening effect of the word garnet, and would at the same time suggest some of the most striking properties of the material.
"Spodumene" furnishes pink to lilac "Kunzite," named after Dr. George F. Kunz, the gem expert, and for a time an emerald green variety was had from North Carolina which became known as "Hiddenite," after its discoverer, W. E. Hidden. No confusion of naming seems to have arisen in regard to this mineral.
The next mineral in the scale of hardness is quartz. (Hardness 7.) When pure and colorless it should be called "rock crystal." Purple quartz is of course amethyst. Some dealers have adopted a bad practice of calling the fine deep purple amethyst "Oriental" amethyst, which should not be done, as the term "Oriental" has for a long time signified a corundum gem. As Siberia has produced some very fine amethysts, the term "Siberian amethyst" would be a good one to designate any especially fine gem.
Quartz Gems. We have already considered the naming of yellow quartz in connection with topaz. "Citrine quartz" is probably the best name for this material. If it is felt that the name "topaz" must be used, the prefix "quartz" should be used, or perhaps "Spanish topaz" will do, but some effort should be made to distinguish it from the true precious topaz. In addition to amethyst and citrine quartz we have the pinkish, milky quartz known as "rose quartz." This is usually correctly named.
"Cat's-eye" is a term that should be reserved for the Chrysoberyl variety, and the quartz variety should always be called "quartz cat's-eye." "Tiger's-eye" is a mineral in which a soft fibrous material has been dissolved away, and quartz has been deposited in its place. "Aventurine quartz" is the correct name for quartz containing spangles of mica. Clear, colorless pebbles of quartz are sometimes cut for tourists. Such pebbles are frequently misnamed "diamonds" with some prefix, as for example "Lake George diamonds," etc. Among the minutely crystalline varieties of quartz we have the clear red, which should be called "carnelian," the brownish-red "sard," the green "chrysoprase," the leek green "prase," and the brighter green "plasma." The last three are not so commonly seen as the first two, and frequently the best-colored specimens are artificially dyed.