Star Sapphire

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Photo courtesy of Scott Papper, GIA GG, AJP, CM (NAJA), Global Gemology & Appraisals

Variety:  Star Sapphire (Designate Fancy Colors - i.e. Black Star Sapphire)
​Species:  Corundum
​​Mohs Hardness:  9 out of 10
Color:  Blue, bluish violet, light to dark violet, greenish blue, black.
RI:  1.76 to 1.77 Spot Reading (Usually Not Detectable)
Birefringence:  0.008 to 0.010
SR/DR/AGG:  DR
Optic Character:  Uniaxial negative
Pleochroism:  None to weak
Fluorescence:  Red & Pink Gems:  Almost inert to strong red or orange red under LW and SW.  Blue Gems:  Weak to strong red under LW and SW.  Dark blue gems are usually inert.
SG:  4.00 (+0.10 / -0.05)

Star sapphire facts

Photo courtesy of Scott Papper, GIA GG, AJP, CM (NAJA), Global Gemology & Appraisals

Star sapphires are a unique gem known for their phenomena called asterism.

Parallel rutile needle inclusions intersecting at 60° angles create this rare phenomena, often amplified by cabochon cutting styles.

Most star sapphires have 6-ray stars.  Synthetic star sapphires will have a perfectly centered, well-defined star while natural star sapphires will often have an off-centered star.  Natural star sapphires with perfectly-centered, well-defined stars can be very valuable due to their rarity.

Star sapphires are currently found in Australia, Myanmar (Burma), Thailand, Sri Lanka, Brazil, Cambodia, Madagascar, United States, Tanzania, Vietnam, Kenya, China, Pakistan, Rwanda, Zimbabwe, and Malawi.

Star sapphires are commonly heated to improve their color and/or clarity.

Star Sapphire Gallery

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