Aroon – Opal and Black Spinel

Opal forms from silica left behind in rock by evaporating water. Precious opal shows flashes of rainbow colour ('play-of-colour') because it is made of tiny stacked spheres that split light into spectral colours.

Birthstone

October

Hardness

5–6.5 (Mohs)

Everyday wear

Opal is soft with very poor to fair toughness, so it scratches easily and is best in earrings and pendants, or in rings with a protective setting and occasional wear.

Care

Warm, soapy water is the only safe way to clean opal. Avoid ultrasonic and steam cleaners, high heat, sudden temperature changes and strong light.

Meaning and tradition

The Romans saw opal as a symbol of love and hope, and in European tradition it stood for hope, purity and truth; because it shows every colour, it was long regarded as the luckiest gem. The idea that opal is unlucky comes from a 19th-century novel, not ancient belief, and opal is the gem for 14th wedding anniversaries.

Spinel occurs in many colours, from orange and vivid red through pink, purple, blue and violet, as well as black. For centuries red spinel was mistaken for ruby.

Birthstone

August

Hardness

8 (Mohs)

Everyday wear

Spinel has good toughness and no cleavage, making it a durable gem for everyday jewellery.

Care

Warm, soapy water is always safe; ultrasonic and steam cleaners are usually fine unless the stone has fractures.

Meaning and tradition

Spinel's name may come from the Latin 'spina' (thorn), and the famous 'Black Prince's Ruby' in England's Imperial State Crown is actually a spinel. In folklore, red gems such as spinel were thought to ease anger and promote harmony, and spinel is a traditional 22nd wedding anniversary gift.