Topaz
Honey yellow. Fiery orange. Cyclamen pink. Icy blue. In warm or cool tones, topaz is a lustrous and brilliant gem.
OVERVIEW
ABOUT TOPAZ
Topaz actually has an exceptionally wide color range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and purple. Colorless topaz is plentiful, and is often treated to give it a blue color. Topaz is also pleochroic, meaning that the gem can show different colors in different crystal directions.
BIRTHSTONES & ANNIVERSARIES
Precious topaz is a birthstone for November and blue topaz is a birthstone for December. Blue topaz is the gem of the 4th anniversary and Imperial topaz is the gem of the 23rd anniversary.
1768
The royal court in Portugal celebrates the discovery of Imperial topaz in 1768.
271 KILOS
A transparent topaz crystal discovered in Minas Gerais, Brazil weighs an astounding 596 pounds.
10 MEV
Irradiating colorless topaz with electrons at energy of 10 million electron volts creates a sky blue color.
FACTS
Chemistry: Al2(F,OH)2SiO4
Color: Yellow, orange, brown, pink to red to purple red, blue, light green and colorless
Refractive index: 1.619 to 1.627
Birefringence: 0.008 to 0.010
Specific gravity: 3.53
Mohs Hardness: 8
TREATMENTS
There are a number of processes used to alter the color, apparent clarity, or improve the durability of gems.
SYNTHETICS
Some gemstones have synthetic counterparts that have essentially the same chemical, physical, and optical properties, but are grown by man in a laboratory.
IMITATIONS
Any gem can be imitated—sometimes by manmade materials or by natural materials chosen by man to impersonate a particular gem.
WHY WE LOVE THIS GEMSTONE
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1
KILOS
Topaz comes in some of the gem world’s largest crystals: the largest are kilos, not carats
2
SLIPPERY
Faceted topaz takes such a high polish it’s slightly slippery to the touch.
3
PLEOCHROIC
Topaz is pleochroic, displaying different colors in different crystal directions.
QUALITY FACTORS
Topaz comes in a variety of colors from shades of blue to the rare reddish imperial colors.
COLOR
The most valued topaz colors are orangy red to red. Blue gems are widely available.
CLARITY
Topaz used in jewelry is typically eye clean with no visible inclusions.
CUT
Topaz crystals are usually columnar, and cut as oval or pear shapes to improve yield.
CARAT WEIGHT
Topaz often forms as large crystals. These can yield sizable cut gems.
TOPAZ QUALITY FACTORS: THE COMPREHENSIVE GUIDE
RESEARCH
Explore sources, gemological research, and the role of gems in history.
