SAPPHIRE BANKSAPPHIRE COLLECTION / STAR SAPPHIRES
Star Sapphires
Star sapphires are among the most visually captivating gemstones in the world. Their defining feature is asterism — a moving 6-ray star formed by intersecting rutile needle inclusions aligned within the crystal. When light strikes the cabochon surface, the star appears to glide. The finest examples combine a crisp, centred star with a rich blue body colour and semi-transparency.
Phenomenon
6-Ray Asterism
Cause
Natural Rutile Needles
Top Origins
Ceylon · Burma
Certification
GRS · GIA · AGL
What is Asterism
Rutile Needle Inclusions
Asterism is caused by three sets of rutile needle inclusions crossing at 60° angles inside the sapphire. When light reflects off these aligned needles, it creates a six-pointed star. The inclusions must be parallel to the crystal's c-axis for the star to appear properly centred.
The Cabochon Cut
Star sapphires must be cut as cabochons — smooth, domed shapes — rather than faceted. The curved surface concentrates reflected light and brings the star to the surface. The cutter must orient the stone precisely so the star appears centred at the top of the dome.
Blue vs. Black Star Sapphires
Blue star sapphires are the most prized, ranging from transparent to semi-transparent with medium to deep blue body colour. Black star sapphires — opaque, iron-rich stones from Thailand — show a silvery or gold star and are significantly more affordable. Grey and white star sapphires also exist.
Why Star Sapphires Are Unheated
Heat treatment dissolves the rutile inclusions that create the star effect. This means virtually all genuine star sapphires are naturally unheated — a quality that adds intrinsic value without the need for additional certification. An intact star is proof of no heat treatment.
Quality Factors
Star Sharpness
Six distinct, well-defined rays
Visible but slightly soft
Broken or faint rays
Centring
Perfectly centred at dome apex
Slight off-centre
Noticeably near edge
Body Colour
Saturated medium to deep blue
Medium blue
Greyish or very pale
Transparency
Semi-transparent, glowing
Slightly translucent
Fully opaque
Origin
Ceylon
Burma (Mogok)
Thailand (black star)
Carat Weight
5 carats and above
2–5 carats
Under 1 carat
2026 Price Reference
| Grade | Blue Star (Ceylon) | Blue Star (Burma) | Black Star |
|---|---|---|---|
| 1–3 ct (Commercial) | $100–$600/ct | $150–$800/ct | $20–$80/ct |
| 3–10 ct (Collector) | $500–$3,000/ct | $800–$5,000/ct | $50–$200/ct |
| 10+ ct (Fine Quality) | $2,000–$8,000/ct | $3,000–$12,000/ct | $100–$500/ct |
| 20+ ct (Exceptional) | $5,000+/ct | $8,000+/ct | By quality |
* Prices are indicative market ranges for natural, unheated stones with sharp centred stars and gemological certification. Individual quality varies significantly.
Star Sapphire Collection
Collection Expanding
Fine star sapphires are exceptionally rare — stones combining a sharp, centred star with rich blue body colour represent only a fraction of supply. We are actively sourcing collector-grade examples from Ceylon and Burma. For bespoke sourcing, contact us directly.
Bespoke SourcingFurther Reading
Star Sapphire Value Guide
Asterism explained, quality factors, and price ranges for blue and black star sapphires.
Blue Sapphire Colour Grades
From Royal Blue to Cornflower Blue — the full colour grading system for fine sapphires.
How to Read a Gemstone Certificate
GRS, GIA, and Gübelin certificate fields decoded, including treatment status.