Opals are rather soft and can scratch easily. Keep them separate from other jewelry and never wear them when doing hard work. Opals must never be stored in a too-dry place, such as a bank vault: They need moisture!
Cultured pearls also love moisture. If they’re constantly exposed to very dry conditions they could crack. They’re especially sensitive to chemicals and acids, and they scratch easily. Keep them away from perfume, hair spray, abrasives, solvents and acetone (nail polish remover).
Turquoise is extremely porous and will absorb just about anything it touches: oil, perfume, soap, etc. Therefore it should be carefully wiped clean rather than washed.
Coral scratches easily and its appearance can be marred by certain chemicals, notably chlorine, alcohol, ammonia and acetone.