September Birthstone

Sapphire is corundum coloured by trace iron, titanium, chromium and other elements. Blue is the classic, from soft cornflower to deep royal blue. Pink sapphire runs from pastel to vivid hot pink, and padparadscha sits in a rare salmon-pink to orange. White sapphire is colourless. Sapphire has long stood for truth, loyalty and wisdom, which is why it shows up in royal regalia and engagement rings, including the Princess Diana sapphire now worn by the Princess of Wales.

Sapphire is 9 on the Mohs scale with very good toughness, which makes it the most popular coloured stone for an engagement ring. It resists scratches and knocks, holds a polish for years, and is safe in most settings without extra protection. Stones with fracture filling need gentler cleaning, but everything else handles daily wear well.

Sapphire has been associated with royalty and divinity since ancient times. Persian myth held that the earth rested on a giant sapphire whose reflection coloured the sky. Medieval clergy wore blue sapphires as a symbol of heaven. The 12 carat oval Ceylon sapphire in the engagement ring given to Princess Diana in 1981 is one of the most famous coloured stones in modern history, and the rise in coloured-stone engagement rings since 2010 traces partly to that ring.

A blue sapphire pendant in white gold reads dressy and timeless. A pink sapphire and rose gold ring suits softer skin tones. For an engagement piece, sapphire is one of the few coloured stones genuinely built for daily wear, and a sapphire halo with a diamond surround is a classic. Lab grown sapphire gives the same hardness and the same colour at a much lower price than a comparable natural stone.

Sapphire is one of the easiest gemstones to live with. Warm soapy water and a soft brush, and most stones are safe for ultrasonic and steam cleaning. The only exceptions are sapphires with significant fracture filling, which need gentler cleaning. Sapphire can scratch softer stones, so store it separately.