Topaz is a gemstone which, throughout history, has shared its name with all other yellow gemstones. It was not until the mid 18th century that the name was assigned to the aluminum fluor-silicate that is uniquely topaz. During the 16th century Cellini described a (most probably) yellow sapphire as "topaz". Due to its close resemblance in color to citrine, yellow to orange "actual topaz" were termed "precious topaz" to distinguish between them. Topaz comes in many hues, from colorless to yellow, blue, brown, red and everything in between. The colorless and pale blue stones are most abundant in nature, followed by yellow and brown stones, while the golden-orange, pinks and reds are most rare. The latter are mostly mined in Brazil.
One particular color - or color range - is of special interest to collectors. It is the saturated golden-sherry or quince-jelly hue (often with a brown modifier) and yellow or pink undertones that is referred to as "Imperial Topaz". How the "Imperial" demarcation came about is subject to speculation with two theories most commonly vying for naming rites. The first theory purports that "Imperial Topaz" was named to honor the Russian Tsar who owned the the Ural mountain Topaz mines, reserving the best quality topaz for the emperor and his family. A second version attributes the name "Imperial Topaz" to the Brazilian Empire. Brazilian/Portuguese Emperor Peter II visited the town of Ouro Preto in 1881 and was presented with a reddish topaz by Professor Henry Gorceix, from that time forward reddish topaz was termed "Imperial". Topaz sellers freely use the term "Imperial" to refer to any topaz with a hint of red or orange, it really only applies to the saturated colors of a small range in hues.
The name Topaz is derived from the island Topazus, just off the coast of Egypt. It is the same island where the best peridots were historically mined (present day Zagbargad). The word topaz comes from the Troglodytae language, an ancient Ethiopian tribe, and means to seek due to the fact that the island was always covered in a fog.
The mining of topaz is strongly associated with tin mining, a mineral needed to create bronze (an alloy of copper and tin) and it is almost certain that the people in the middle-eastern bronze age would have known about this gemstone . In Europe the stone became highly popular after the topaz discoveries in Brazil during the 18th century and by the turn of the 19th century yellow and pink topaz were all the fashion and were extensively used throughout most of the 1800's. Although open à jour settings were employed since the end of the 17th century, most topaz was still set in closed-back settings with a back foil to intensify their hue. This was especially true when several stones were set in a cluster or when a complete rivière was to be crafted, as the foil helped create matching colored stones. For smaller individual stones, as used in the regard jewelry from around 1840, this was not deemed necessary. Topaz was used to represent the letter T, in either pink or yellow colors.
Pink topaz does exist in nature, but it is rare and mostly pale in color. In order to improve the color these stones were pinked by foiling them with a red foil. Colorless topaz was also treated in this fashion. Another way of pinking topaz is through the slow heating of yellow stones, up to temperatures of 500 degrees Celsius, followed by a slow cooling. The latter method has been practiced since the 18th century and one can safely assume that most pink topaz have gone through one of these treatments.
Many of the blue topaz that we see in jewelry today have undergone an irradiation treatment to produce a stable color of varying saturation. The lighter shades are termed sky blue, the medium range Swiss blue and the darker toned blue topaz are sold as London blue. White topaz is readily available and has a high luster. They are so clear that they were described as water drops by the Brazilian miners. The Portuguese - who owned the mines - termed them slaves' diamond in reference to the slaves who worked the mines in the region around Ouro Preto.
Topaz is a relatively hard stone, harder than quartz but softer than corundum, which makes it suitable for jewelry. This gem however suffers from a perfect cleavage in one direction (the basal plane) so it is a stone that must be handled with some care. A hard knock in the right - or wrong, depending on which viewpoint you take - direction will split the stone in half. In this regard it is in good company as diamond likewise suffers from directional cleavage. Colorless and blue stones are usually cut with the table a few degrees off this cleavage direction so they can hold a good polish. The more costly imperial topazes are cut with the cleavage plane perpendicular to the table of the gemstone, mostly for weight retention of the rough material which can be very costly (a multitude of a 100 compared to the price of blue topaz). This poses a problem during setting of a stone as it can easily break. The wearer should be aware of the cleavage plane and know that it is best not to expose topaz to heat or ultrasonic cleaning.
|Gemological information for topaz|
|Color||Colorless, Blue, Pink, Yellow, Green, "Mystic" Colors|
|Treatments||Irradiation, Heat Treatment, Coatings|
|Country of Origin||Brazil|
|Ultrasonic Cleaning||Not Safe|
|Steam Vleaning||Not Safe|
|Warm Soapy Water||Safe|
|Light Sensitivity||Usually Stable|
|Heat Sensitivity||May Fracture|