Judging quality
Most blue topaz is irradiated colorless material, which is standard and stable. Imperial topaz is naturally colored, far rarer and priced accordingly. Look for clean terminations on specimens.
Silicate
Topaz
A very hard silicate that grows in glassy prismatic crystals. Imperial topaz, the sherry-orange to pink material from Ouro Preto, is the aristocrat of the family.
Care
Hard but with perfect basal cleavage; a sharp knock in the wrong plane will split it. Avoid ultrasonic cleaning.
History & lore
Brazil's Ouro Preto district has been the sole significant source of imperial topaz since the eighteenth century.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Topaz
- What is Topaz?
- A very hard silicate that grows in glassy prismatic crystals. Imperial topaz, the sherry-orange to pink material from Ouro Preto, is the aristocrat of the family.
- How hard is Topaz and what is it made of?
- Topaz is a Silicate-family mineral with the composition Al2SiO4(F,OH)2. It crystallizes in the orthorhombic system and rates 8 on the Mohs hardness scale. It occurs in colorless, blue, golden, pink.
- Where does Topaz come from?
- Notable localities for Topaz include Brazil (Minas Gerais), Pakistan, Russia, Nigeria.
- How do you tell good Topaz from filler?
- Most blue topaz is irradiated colorless material, which is standard and stable. Imperial topaz is naturally colored, far rarer and priced accordingly. Look for clean terminations on specimens.
- How do you care for Topaz?
- Hard but with perfect basal cleavage; a sharp knock in the wrong plane will split it. Avoid ultrasonic cleaning.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.