Blue Topaz

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David Yurman Swiss blue topaz and diamond pendant

Species:  Topaz
Mohs Hardness:  8 out of 10
Color:  Light toned blue and slightly greenish blue to dark toned strongly greenish blue
RI:  1.619 to 1.627 (+/-0.010)
Birefringence:  0.008 to 0.010
SR/DR/AGG:  DR
Clarity Type:  Type I
​Optic Character:  Biaxial positive (common point is 0.001 from the low RI)
Pleochroism:  Usually blue and colorless
Spectrum:  Not diagnostic
Fluorescence:​  Variable
SG:  3.53 (+/-0.04)

Blue Topaz Facts

Emerald cut blue topaz

Although topaz occurs in nearly every color, blue topaz is the most popular of all topaz colors.
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Some topaz crystals are so large that they are weighed in kilos, not carats.
 
Topaz can take such a high polish that it is slippery to the touch.

Although usually undetectable, most blue topaz has undergone a routine irradiation and heating process to achieve its attractive blue coloration.

Swiss Blue Topaz is bright blue, light in tone.

London Blue Topaz is a darker blue, dark in tone.
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Blue topaz is a December birthstone and the 4th wedding anniversary gemstone.​
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Blue Topaz Gallery

All photos courtesy of Scott Papper, GIA GG, AJP, CMA (NAJA)