Moonstone

Adularescence - a moonlit glow that drifts across the gemstone.

Mohs hardness: 6–6.5
Crystal system: Monoclinic
Composition: KAlSi₃O₈
Colours: White with blue sheen ('blue moonstone'), Peach, Grey
Origins: Sri Lanka, India, Madagascar
Birthstone: June

Moonstone's signature shimmer - adularescence - comes from light scattering between alternating microscopic layers of orthoclase and albite. Sri Lankan blue moonstone is the historic benchmark.

Popularised by Art Nouveau jewellers (especially René Lalique) and again by 1960s and 1990s designers.

Treatments

What to know

Generally untreated

Care & handling

How to wear it

Cleaves easily - protect from impact
Warm soapy water; avoid ultrasonic

Jewellery use

Setting the gemstone

Pendants, earrings and protected ring settings.