Judging quality
Benitoite fluoresces a striking chalk blue under shortwave UV — the fastest field test there is. Crystals are flattened triangles, unlike any sapphire habit.
Silicate
Benitoite
California's state gemstone and a genuine local rarity: sapphire-blue triangular crystals in white natrolite, from one small serpentinite body in San Benito County. The mine is effectively worked out, which makes every good specimen finite.
Care
Reasonably hard but with distinct cleavage-free brittleness; avoid knocks. Ultrasonics are risky on matrix pieces.
History & lore
Discovered in 1907 and initially mistaken for sapphire; it is one of very few gem minerals known essentially from a single place on earth.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Benitoite
- What is Benitoite?
- California's state gemstone and a genuine local rarity: sapphire-blue triangular crystals in white natrolite, from one small serpentinite body in San Benito County. The mine is effectively worked out, which makes every good specimen finite.
- How hard is Benitoite and what is it made of?
- Benitoite is a Silicate-family mineral with the composition BaTi(Si3O9). It crystallizes in the hexagonal system and rates 6-6.5 on the Mohs hardness scale. It occurs in blue, deep blue, violet-blue.
- Where does Benitoite come from?
- Notable localities for Benitoite include San Benito County, California, USA.
- How do you tell good Benitoite from filler?
- Benitoite fluoresces a striking chalk blue under shortwave UV — the fastest field test there is. Crystals are flattened triangles, unlike any sapphire habit.
- How do you care for Benitoite?
- Reasonably hard but with distinct cleavage-free brittleness; avoid knocks. Ultrasonics are risky on matrix pieces.
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.