oxides
Sapphire
Al2O3
- Also known as
- padparadschastar sapphire
- Crystal system
- trigonal
- Hardness
- 9 on the Mohs scale
- Lustre
- adamantine
- Colour
- Blue classically, but also pink, yellow, green, orange and colourless
- Where it forms
- In metamorphic and igneous rocks poor in silica, and concentrated in alluvial gravels where it survives weathering.
- Chiefly from
- Sri LankaMadagascarKashmirMontana, United StatesQueensland, Australia
Why it is that colour
Blue comes from iron and titanium together, transferring charge between them. Other colours come from other combinations. Any gem corundum that is not red is a sapphire, which makes "sapphire" a category defined by exclusion.
Safety
No hazard from handling. The overwhelming majority is heat-treated; beryllium diffusion treatment is also used and is much harder to detect.
Where it comes from
Sri Lanka has been mined for over two thousand years and remains a major source with largely small-scale, regulated operations. Madagascar’s deposits, found in the 1990s, triggered rushes with severe environmental and social consequences including mining inside protected forest.
Historical use
Kashmir sapphires, from a deposit worked for only a few decades after 1881 and long exhausted, remain the most valuable by reputation. Australia was for a period the largest producer by volume, from the Queensland and New South Wales fields.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Ancient and well documented, though the classical word sapphirus often meant lapis lazuli rather than corundum, which makes older references ambiguous. Medieval European tradition treats it as the stone of clergy and of heaven, and the association with wisdom and truth runs continuously from there.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
The word sapphire is a category rather than a description. Corundum coloured red is ruby; corundum coloured anything else is sapphire, including colourless. So a yellow sapphire and a blue sapphire have less to do with each other than a ruby and a sapphire do — and the line between a pink sapphire and a ruby is a commercial judgement that different markets draw in different places.
You are almost certainly carrying synthetic sapphire. It is the scratch-resistant cover over most phone camera lenses and the glass on most good watches, grown by the tonne and valued for hardness alone.
Identity checked against IMA-CNMNC master list, June 2025.