Judging quality
The finest is Sri Lankan: near-colorless and transparent with a strong blue sheen that seems to hover below the surface. Cloudy white material with weak silvery shimmer is far more common.
Feldspar
Moonstone
Orthoclase feldspar with a floating blue-white sheen called adularescence, caused by light scattering between microscopic layers of two feldspars.
Care
Relatively soft with good cleavage. Store apart from harder stones.
History & lore
Roman naturalists believed moonstone waxed and waned with the moon; it became the signature stone of Art Nouveau jewellery under Lalique.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Moonstone
- What is Moonstone?
- Orthoclase feldspar with a floating blue-white sheen called adularescence, caused by light scattering between microscopic layers of two feldspars.
- How hard is Moonstone and what is it made of?
- Moonstone is a Feldspar-family mineral with the composition KAlSi3O8. It crystallizes in the monoclinic system and rates 6-6.5 on the Mohs hardness scale. It occurs in white, peach, grey, blue.
- Where does Moonstone come from?
- Notable localities for Moonstone include Sri Lanka, India, Madagascar, Tanzania.
- How do you tell good Moonstone from filler?
- The finest is Sri Lankan: near-colorless and transparent with a strong blue sheen that seems to hover below the surface. Cloudy white material with weak silvery shimmer is far more common.
- How do you care for Moonstone?
- Relatively soft with good cleavage. Store apart from harder stones.
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.