Judging quality
Slender monoclinic prisms with brilliant faces; cleavage flashes show as internal mirror planes. Any faceted stone is the work of a specialist.
Silicate
Euclase
A collector's gem in soft aquamarine blue, notoriously difficult to cut because of perfect cleavage — the name means 'easily broken'. Colombian crystals from the emerald belt are the finest blue known.
Care
Cleavage is perfect and unforgiving. Store padded and alone; never ultrasonic.
History & lore
René Just Haüy named it in 1792 after breaking a crystal while examining it.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Euclase
- What is Euclase?
- A collector's gem in soft aquamarine blue, notoriously difficult to cut because of perfect cleavage — the name means 'easily broken'. Colombian crystals from the emerald belt are the finest blue known.
- How hard is Euclase and what is it made of?
- Euclase is a Silicate-family mineral with the composition BeAlSiO4(OH). It crystallizes in the monoclinic system and rates 7.5 on the Mohs hardness scale. It occurs in pale blue, blue, colorless.
- Where does Euclase come from?
- Notable localities for Euclase include Colombia (Chivor), Brazil (Ouro Preto), Zimbabwe, Tanzania.
- How do you tell good Euclase from filler?
- Slender monoclinic prisms with brilliant faces; cleavage flashes show as internal mirror planes. Any faceted stone is the work of a specialist.
- How do you care for Euclase?
- Cleavage is perfect and unforgiving. Store padded and alone; never ultrasonic.
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.