Information
INTRODUCTION TOPAZ
The name “imperial topaz” is said to have originated in the 19th century in Russia, where the Ural Mountain mines were an important source. According to some sources, pink topaz from those mines was restricted to the family of the Czar. Today, the gem trade generally uses the term for pink, orange and red topaz, which comes mainly from Ouro Prêto.
COLOR ,CLARITY AND CUT
Topaz commonly occurs in colorless and brown colors, it is the rare golden, orange, pink, red and purple colors, which are often termed “precious” or “imperial” topaz, that are the mainstay of the fine gem market. While blue topaz is found in nature, most of the material is produced by a combination irradiation/heating treatment.
Yellow and brown topaz owe their color to color centers. The impurity chromium produces pink to red colors. A combination of color centers and chromium produces orange topaz. Blue topaz is colored by color centers. Topaz from most sources is reasonably clean. Thus eye-clean stones are both desirable and possible. The exception is with pink and red topaz, where only small stones are normally available. In those colors, a slightly higher degree of inclusions are tolerated. Topaz is generally cut as elongated stones, typically emerald cuts, elongated ovals, cushions and pears. To save weight, pears in particular are often cut with overly narrow shoulders. Due to the huge production, blue topaz is cut in virtually any shape and style one can imagine. Cabochon-cut topazes are rarely seen.
While topaz does have a perfect basal cleavage, it is not an easy cleavage, and so does not present too much difficulty to the cutter. Nevertheless, cutters will often try to ensure that no facet is parallel to the cleavage direction and jewelers try to mount valuable stones in settings that protect the stone.
Treatment: There are many treatments applied to Topaz. White topaz is in ready supply, and lending itself to methods to make it more interesting and saleable. The most common treatment is to irradiate the white stone to give a range of blues. Depending on the length of time, strength and type of radiation used, the shade of blue varies from Sky Blue through Swiss Blue to the deepest London Blue. Doubts have been expressed for some time as to the safety of irradiated stones and important into the USA was halted for a while until safety for the wearer could be assured. Coating with titanium results in ‘Mystic Topaz’,an eye-catching stone that has a wide range of colours and patterns but remains low in value .Cobalt diffusion is also used to enhance Topaz. These coatings are subject to abrasion. The range of colours of coated topaz is phenominal- and cheap .Blue can occur naturally but is rare
VALUE
The value of topaz are, like any gem, dependent on quality. Blue topaz, the most common seen in jewelry today, has been produced in such quantities that today it is generally available for $25/ct. at retail for ring sizes. Larger sizes may be slightly more. While natural blue topazes are known, the huge production of treated blue topaz has essentially dropped the price of the natural blue down to that of the treated stone.
Colorless topaz, from which blue topaz is produced ‘via irradiation and heat’, is available in sizes up to 100 cts. and greater, and sells for less than $8/ct. Brown topaz fetches similar prices. In contrast, precious topaz in rich orange colors fetches prices in excess of $1000/ct. for large (10 ct. +) sizes. The most valuable topaz is a rich pink or red color, and can reach $3500/ct. at retail. These are rare in sizes above 5 cts. Visit our dubai online shopping and we can assist you with the right information about the value of Topaz and about any other gold stones.
TOPAZ GEMSTONE PROPERTIES
| Composition | Topaz has the following composition: Al2(F,OH)2SiO4 |
| Hardness (Mohs) | 8 |
| Specific Gravity | 3.53 ± 0.04 |
| Refractive Index | 1.619–1.627 (±0.010) |
| Crystal System | Orthorhombic; usually occurs as vertically striated elongated prisms topped by domes |
| Colors | Orange, yellow, brown, blue, pink, colorless, rarely red |
| Pleochroism | Weak to moderate, dichroic |
| Dispersion | 0.014 |
| Phenomena | None |
| Handling | Ultrasonic: not safe; never clean topaz ultrasonically Steamer: not safe The best way to care for topaz is to clean it with warm, soapy water. Avoid exposure to heat, acids and rapid temperature changes. Strong heat may alter or destroy color. |
| Enhancements | Various Most blue topaz is made by irradiation and then heat; this treatment is undetectable and extremely common. Blue topaz irradiated with in nuclear reactors can emit dangerous levels of radiation; it must be allowed to cool down to safe levels before sale. Some orangy topaz is heated to destroy the color centers, leaving behind the chromium-caused pink color. |
| Handling | Ultrasonic: not safe; never clean topaz ultrasonically Steamer: not safe The best way to care for topaz is to clean it with warm, soapy water. Avoid exposure to heat, acids and rapid temperature changes. Strong heat may alter or destroy color. |
| Synthetic available? | No |
ORIGIN AND IMITATION
Topaz Gem has been found at a number of localities around the world, including, Sri Lanka, Russia, Nigeria, Burma, Brazil Pakistan, USA and Mexico. The premier source is near Ouro Prêto in Brazil’s Minas Gerais state. Topaz has never been synthesized, but a number of imitations exist, including natural stones such as citrine and smoky quartz, and man-made imitations such as glass.
NAME, FAME AND LEGEND
Topaz is the name for the mineral species that is number 8 on Mohs’ scale of hardness. There is some uncertainty regarding the name. Some say it comes from the Sanskrit word meaning “fire.” Others link it to the Red Sea Island of Topazios (Zabargad or St. John’s Island), where peridot has been found. For the general public, topaz means a yellow gem, and much citrine and smoky quartz has been sold as “golden topaz” and “smoky topaz.” The terms “imperial” and “precious” topaz are often used to distinguish between true topaz and the quartz look-alikes.
The name “imperial topaz” is said to have originated in the 19th century in Russia, where the Ural Mountain mines were an important source. According to some sources, pink topaz from those mines was restricted to the family of the Czar. Today, the gem trade generally uses the term for pink, orange and red topaz, which comes mainly from Ouro Prêto, Brazil. Fine pink topaz also comes from the Katlang area of Pakistan.
