Origin of Natural Topaz and its Variety
In ancient times, just about any yellow gem was likely to be called topaz. The name itself may have been derived from a Sanskrit word meaning “fire” The association of topaz and the color yellow is unfortunate since fine topaz occurs in colorless crystals, as well as pink, blue, green, and a pleasing “Sherry” color.
The jewelry trade has created a host of terms for the sale of yellow gems. For example, we find “smoky topaz,” which is actually smoky quartz; “citrine topaz” “Bohemian topaz” and “occidental topaz” which are all citrine; “Oriental topaz,” which is yellow corundum. Most of the stones sold as “topaz” today are actually citrine. True topaz is labeled properly with only two modifying terms: “precious” and “imperial” the latter referring to a Brazilian occurrence.
The most important color variety of topaz is the range of yellow and brown gems, mined chiefly at Ouro Preto, Brazil. Some of this material actually attains a right-red hue. Golden-brown topaz is the most expensive color variety, with large faceted gems commanding prices of several hundred dollars per carat.
Related to the brownish stones is pink topaz because it has been found that some sherry-colored and yellow material will turn pink on heating. True pink topaz does occur in nature but is extremely rare. A rare light-violet topaz color has also been observed.
Colorless topaz is both attractive and inexpensive. Proper cutting can yield bright and sparkling gems, but the lack of color reduces its demand and keeps its price low. Blue topaz, on the other hand, has become increasingly popular. This is partly due to the surge in the Popularity of aquamarine. Fine aquamarine has become so expensive and scarce that blue topaz has begun to find wide use as a substitute. Most blue topaz is fairly pale, but some material can apparently be turned a deep color by irradiation with gamma rays. Green and greenish-yellow gems are occasionally Seen in the gem trade, but these are rare and not generally known to the buying public. There is currently no effective distinguishing test for irradiated blue topaz or heat-treated pink topaz. Purchase of such stones should always be accompanied by some statement indicating natural origin or prior treatment.
Topaz usually forms late in the crystallization of rocks. It is typically found in pegmatite dikes, and crystals can reach enormous size. Golden-brown crystals up to a foot in length are known, but even these are dwarfed by the 100-pound behemoths found in Brazilian deposits. Some of these crystals are perfectly formed and nearly completely transparent.
Topaz is very hard,8 on the Mohs scale, so it wears well in jewelry. Its only drawback is a well-developed cleavage, making the cutting of topaz gems a tricky business. A casual blow to a cut topaz could cause it to split, so rings should be treated with some care. Topaz takes a high polish and makes a spectacular jewelry stone. Its specific gravity is much higher than the typical quartz imitations, so unset stones are fairly easy to distinguish just based on “heft”
Some topaz tends to fade in sunlight. This is especially true of pale-brown material from the U.S.S.R. and Mexico, as well as from Japan and the Thomas Range, Utah. Sometimes irradiated stones will also bleach out in sunlight, but the dark-blue material seems to be fairly stable.
Topaz occurs in many localities throughout the world. Brazil is the chief supplier of colorless, pale-sherry, and blue varieties. Ouro Preto, Brazil is the world’s chief source of fine golden and yellow topaz. Mining is a hand operation, and the total output per day is quite small, contributing to the scarcity of these stones.
A fine blue and greenish crystals come from the Ural Mountains, U.S.S.R., and these are avidly sought By collectors. Colorless, yellow, and sherry-colored topaz is found in San Luis Potosi and Durango, Mexico. Good crystals come from Japan, the Malagasy Republic, Ireland, Rhodesia, Nigeria, and, in the United States, Colorado, Maine, post-Hampshire, and Utah. Topaz is abundant in the gem gravels of Burma and Sri Lanka, where it is recovered as a by-product in the mining of ruby and sapphire.
Topaz has not been synthesized in the laboratory on a commercial basis. So-called “synthetic topaz” is actually synthetic corundum that has been made in a suitable color.
Consumer Tips – The most frequently misused items in the gem trade include “smoke topaz” “citrine topaz,” and related names. These are tradenames devised by jewelry sellers to sell quartz, a common, inexpensive gem material, as topaz a fairly rare, costly gem with optical properties superior to those of quartz. Loose gems of topaz and quartz can easily be distinguished based on heft (the topaz has a much) higher specific gravity) and brilliance (topaz has a higher refractive index). Set stones, especially when small, can be difficult or impossible to distinguish with the naked eye.
In purchasing a yellow stone labeled “topaz” the buyer should always insist on verification and guarantee of the authenticity and natural origin of the stone. Suspicion should be aroused if a “topaz” ring containing a large yellow-orange stone is priced at only $100 or $200. If the stone is precious topaz, its value might be more than $100 per carat, exclusive of the setting.
Blue topaz has appeared on the gem market in increasing quantities. This is largely due to the escalating price of aquamarine, and the need for an inexpensive, natural blue gem on the marketplace. To Many jewelers, however, the material is sufficiently posted that a customer bringing a blue topaz to a shop for evaluation might be met with the comment “that can’t be topaz, there is no such thing as blue topaz.” This problem will diminish as more blue topaz is seen in the jewelry trade
Topaz, although listed as the birthstone for November, is seldom seen except in the large jewelry shops. This is a shame, because in white and pale colors topaz may cost only a few dollars per carat. There is enough such material available to make distribution possible on a much wider scale than currently seen.