KhyatiGems knowledge library
Blue Sapphire
Blue sapphire is a blue variety of corundum. It shares its mineral species with ruby and sapphires of other colours. The familiar blue name does not identify a particular geographic source or establish that a specimen is untreated.
AI-assisted source review · 2026-10-16. No named gemologist review is claimed. How this reference was reviewed.
PumpkinSky · CC BY-SA 3.0 · Source · CC BY-SA 3.0
Also known as: Neelam, नीलम.
| Mineral species | Corundum |
|---|---|
| Mohs hardness | 9 |
| Refractive index (reference range) | 1.762–1.770 |
| Birefringence (reference range) | 0.008–0.010 |
| Specific gravity (reference value) | Approximately 4.00 |
| Chemical composition | Al₂O₃ |
Classification and appearance
GIA describes blue sapphire hues from greenish blue to violetish blue. Those colour directions are useful descriptive terms, not proof of origin. Compare an individual stone under consistent conditions and ask which photographs represent its everyday appearance.
When reading a trade description, separate observations about colour from claims about treatment and provenance. Each claim answers a different question. A photograph that looks strongly blue cannot substitute for a laboratory examination or a clear treatment disclosure.
Treatments and disclosure
Sapphire treatment information should be recorded for the particular stone. Heating, diffusion and filling are different subjects, and care should take account of any disclosed enhancement. Ask whether the report addresses treatment, what language it uses and whether the seller has provided additional care instructions. Avoid assuming that every sapphire needs identical handling.
Identification and documentation
A name on a label is a starting point, not a laboratory conclusion. Ask whether the material has been identified as natural or laboratory grown, which treatments were detected, and which questions the examination actually addressed. Read the report for the individual stone rather than borrowing a conclusion from a similar-looking example.
Keep the report number, stone measurements and seller description together when discussing a purchase. If any of those details disagree, pause and ask for clarification. A reference photograph on this website is an educational example; it cannot establish the identity, treatment or geographic origin of a stone in another listing.
Care and cleaning
Sapphire rates 9 on the Mohs scale. GIA distinguishes the care of untreated or heated sapphire from filled or dyed material. When the treatment or condition is uncertain, seek stone-specific instructions before using an ultrasonic or steam cleaner. Store it so that it cannot rub against other jewellery.
Questions to ask before choosing a stone
Request clear photographs under more than one lighting condition and ask which image best represents the stone in ordinary use. Compare dimensions as well as weight, and ask about any treatment-related care requirements before deciding on a setting. These questions are useful even when the gemstone name is familiar.
Do not infer the terms of a sale from this educational article. Availability, a particular report, delivery and return conditions belong to the individual seller and purchase channel. Keep written answers with the relevant listing information so that your decision is based on the stone being offered.
Reading the property table
The optical and density values here are reference ranges from GIA, not measurements of a pictured specimen. A property table helps you understand the material being discussed; it is not a substitute for a laboratory examination. Results depend on the sample, instrument and method, and more than one observation may be needed to distinguish natural, synthetic and treated material. Ask for the conclusions of the examination rather than attempting to identify an unknown stone from one number.
Frequently asked questions
What is blue sapphire?
Blue sapphire is a blue variety of the mineral corundum.
What does Neelam refer to?
Neelam is a traditional Indian name commonly used for blue sapphire; it is not a separate mineral species.
Sources and further reading
- GIA — Sapphire description Checked 2026-10-16
- GIA — Sapphire care and cleaning Checked 2026-10-16
- GIA Blue Sapphire reference properties Checked 2026-10-16