Composition
Calcium carbonate (aragonite) in a matrix of conchiolin
Hardness · Crystal system
2.5–4.5 · Orthorhombic (aragonite)
Mined in
Japan, China, Australia, French Polynesia, Philippines
Soft enough to scratch with a fingernail and dissolved by acid — perfume, vinegar and sweat all damage it.
Traditionally associated with sincerity, emotional maturity and quiet dignity.
Care. Wipe with a damp cloth after wearing. Put pearls on last, after perfume and hairspray, and never soak them.
Spotting a fake. The tooth test still works: rub the pearl gently against a tooth edge. Real nacre feels gritty; plastic and glass feel glassy-smooth.
Composition
Potassium aluminium silicate (KAlSi₃O₈) — feldspar
Hardness · Crystal system
6–6.5 · Monoclinic
Mined in
Sri Lanka, India, Madagascar, Myanmar
The floating blue glow is adularescence — light scattering between microscopic layers of two feldspars, not an inclusion or a coating.
Traditionally linked to intuition, cycles and new beginnings.
Care. Soapy water and a soft cloth. Never ultrasonic — feldspar cleaves easily and vibration can split it.
Spotting a fake. Opalite and milky glass are the usual substitutes. Real moonstone shows adularescence that moves as you tilt it; glass shows a static sheen that stays put.
Composition
Beryllium aluminium oxide (BeAl₂O₄) — chrysoberyl coloured by chromium
Hardness · Crystal system
8.5 · Orthorhombic
Mined in
Russia (Ural), Brazil, Sri Lanka, Tanzania
Genuine colour-change alexandrite is rarer than diamond. Most stones sold under the name are synthetic corundum.
Traditionally associated with adaptability and holding two truths at once.
Care. Warm soapy water. Hard enough at 8.5 to be safe in most settings.
Spotting a fake. Almost everything sold as alexandrite is synthetic colour-change corundum. Genuine alexandrite shifts green to red; the imitations shift blue-violet to purple, which is a different change entirely.