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Introduction:
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Topaz was once a name used loosely to describe any brown and yellow gemstones, regardless of actual composition. Today, however, the word refers specifically to stones that are members of the mineral species, topaz, which is recognized as the November birthstone. Topaz is available in a wide range of colors, but most emphasis goes to nicely colored yellows, oranges, and blues. Blue topaz, in fact, has become so popular in recent years, that jewelers often stock more of the blue variety than the more expensive precious yellow stones. The blue stones are generally irradiated and heat treated, which has been a point of controversy for years. The debate over whether such stones are natural or lab-created is loosing ground to the sheer economics of customer demand in the U.S. Blue topaz is the best selling non-traditional colored stone in the country. The truth of the matter is that topaz is a natural substance and the blue color is lab created. Supporters of the process remind others that many stones are heat treated to promote their best qualities and diamonds are often irradiated for the same reason. |
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History
of...
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Topaz was first discovered on an island in the Red Sea now known as Zebirget. It draws its name from the earlier name of that island, Topazos. The most famous topaz mine in the 18th century was at Schneckenstein in Saxony. Today, Mina Gerais, Brazil is the most important supplier. The availablity and popularity of blue topaz is a relatively new occurrence, and controversy has swirled around the practice of irradiating and heating colorless and brown topaz to create the much sought-after blue stones. Blue topaz gained popularity first in the United States, as bargain-conscious consumers realized it offered deep color at a fraction of the cost of aquamarine. It seems that today's market supports blue topaz on its own merit, without the stigma of being an aquamarine replacement.
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Technical
Specifications:
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| DESCRIPTION |
| Topaz is a mineral species. |
| Chemical
Composition: |
Al2(F, OH)2SiO4 |
| Appearance: |
•Transparent
• Colorless, yellow, orange, brown, pink to red to purple-red, light to dark blue, light green
•Some blue and yellow-orange topaz demonstrate chatoyancy, but this is rare. |
| Misnomers: |
Colorless topaz is sometimes incorrectly referred to as "slave's diamond," and blue topaz is sometimes called Brazilian Sapphire. Neither of these terms are correct. |
| Typical
Sizes: |
• Orange, red, pink, and yellow: 1-8 ct; faceted stones over 30 ct are rare
• Blue: 5-25 ct; faceted stones of more than 2000 ct have been cut for museums |
| Cut Styles: |
Faceted |
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| IDENTIFICATION |
| Optic
Character: |
DR, biaxial positive |
| Refractive
Index: |
1.619-1.627 (+/-.010) |
| Birefingence: |
.008 to .010 |
| Dispersion: |
.014 |
| Pleochroism: |
• Yellow: weak to moderate brownish yellow, yellow and orange-yellow
•Brown: weak to moderate yellow-brown and brown
• Red and Pink: weak to moderate light red and orangy red to yellow
•Green: weak to moderate blue-green and light green
•Blue: weak to moderate, different tones of blue |
| Ultraviolet
Fluorescence: |
• Yellow to brown, pink to red: weak to moderate orange-yellow (LW); generally weaker (SW); some pinks--moderate greenish white (SW)
• Blue, colorless: inert to weak yellow or green (LW); generally weaker (SW) |
| Absorption
Spectra: |
Not diagnostic |
| Cause
of Color: |
• Pink, red: chromium
•Blue, yellow, brown: various color centers
• Orange: color centers and chromium |
| Specific
Gravity: |
3.53 (+/-.04) |
| Polish
Luster: |
Vitreous |
| Fracture: |
Conchoidal |
| Luster: |
Vitreous |
| Cleavage: |
Perfect in one direction |
| Indentifying
Characteristics: |
Inclusions containing two or more nonmiscible liquids; 2-phase or 3-phase inclusions |
| Known
Enhancements: |
• Heating is commonly used to change brown, yellow, and/or orange topaz to pink or red. The treatment is stable, undetectable, and requires no special care.
• Heating is also commonly used on irradiated stones to draw out a blue color. This type of heating is generally undetectable, though it can sometimes be found by thermoluminescence. Avoid high heat with heat-treated, irradiated stones.
•Irradiation is commonly used to turn some colorless topax to brown or brownish green. This is generally the first step to creating treated blue topaz. At this stage, the color can fade and we recommend avoiding high heat and prolonged exposure to strong light. If the stone is radioactive, which is rare, avoid handling and wearing. |
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| DURABILITY RATINGS |
| Hardness: |
8 |
| Toughness: |
Poor; dropping the stone on a hard surface, or light blows, may cleave topaz |
| Topaz is sometimes mistaken for: Apatite, aquamarine, brazilianite, chrysoberyl, citrine, danburite, orthoclase, phenakite, ruby, sapphire, spinel, tourmaline and zircon |
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Care
Tips:
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| Cleaning Methods |
| •Ultrasonic: |
Never |
| •Steamer: |
Never |
| •Warm
soapy water: |
Safe |
| Stability of Stone |
| •Heat
tolerance: |
Rapid heating or cooling will cause internal breaks; strong heat may alter or destroy color |
| •Light
tolerance: |
Some brown stones fade |
| •Chemical tolerance: |
Affected very slightly |
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Recommended
Uses:
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Rings
- Topaz is popular in rings today based on affordability and beauty. Topaz rings are not necessarily the best idea but if cared for will work fine. Topaz is a hard stone but lacks a little in toughness making it somewhat vulnerable to abuse. Rings are subject to much wear and tear and should be considered when purchasing a topaz ring. On the other hand, topaz is very affordable and can easily be replaced if necessary. Earrings
- Earrings to go with a nice topaz pendant or ring are a perfect addition to any jewelry collection. Available in blue, pink and yellow topaz offers a variety of colors, shapes and sizes. Topaz earrings should be plenty durable to withstand normal wear. The most abuse will likely come inside the jewelry box. Show loving care and topaz will last for many years of pleasure.
Pendants - Blue and yellow topaz is likely the best choice for a pendant due to large sized stone availability. Great for both formal and informal occasions, topaz will show a diverse array of taste in jewelry. Be careful with topaz pendants because they may have a tendency to get banged around.
Bracelet - Topaz bracelets as far as wear are not recommended but when it comes to avialability and affordability they are perfect. Its should be no problem to find a matching set of stones for this application. Topaz can be replaced with relative ease if the occasional breakage should occur.
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Source
Map:
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| All technical specifications and care
tips on this page was referrenced from the "Gem
Reference Guide" published by the Gemological Institute
of America |
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