Buying guide

Topaz

Sky blue, Swiss blue and London blue describe increasing depth of colour, not different species. Imperial topaz, the natural golden to peach-pink material, is far rarer than any blue topaz and priced accordingly.

Topaz at a glance

Mineral family: Topaz
Chemical formula: Al2SiO4(F,OH)2
Mohs hardness: 8
Refractive index: 1.609 - 1.643
Specific gravity: 3.53
Crystal system: Orthorhombic
Colours: blue, golden, pink, colourless
Birthstone month: November, December
Anniversary: 4th & 23rd
Typical treatment: Blue topaz is almost always irradiated and heated colourless topaz. The treatment is permanent and the material is safe. Imperial topaz is naturally coloured.
In stock now: 16 stones from $77.50

What drives the price

In one line: Natural vs treated colour, size, cut precision.

Treatment

Blue topaz is almost always irradiated and heated colourless topaz. The treatment is permanent and the material is safe. Imperial topaz is naturally coloured.

Any seller unwilling to state treatment in writing is telling you something. Every listing on this site states it.

Durability and daily wear

Topaz has perfect basal cleavage, a sharp knock in the wrong direction can split it regardless of its hardness. Never ultrasonic or steam. Avoid prolonged strong light for pink material.

Mohs 8, orthorhombic crystal system, specific gravity 3.53.

Tradition and meaning

Blue topaz is a throat chakra stone of clear communication. Imperial and golden topaz are associated with confidence and personal power.

Birthstone for November and December. Associated with Sagittarius and Scorpio. Anniversary stone: 4th & 23rd.

Frequently asked

Is blue topaz natural?

The material is natural topaz, but the blue colour is nearly always produced by irradiating and heating colourless topaz. The colour is permanent and the stones are safe to wear. Naturally blue topaz exists but is pale and commercially rare.

What is imperial topaz?

Imperial topaz is the naturally golden-orange to pinkish material, historically from Ouro Preto in Brazil. It is not irradiated, is far scarcer than blue topaz, and holds its value much better.

Why does topaz chip if it is hardness 8?

Hardness measures scratch resistance, not toughness. Topaz has one direction of perfect cleavage, so an impact aligned with that plane can cleave the stone cleanly even though it resists scratching very well.