Yemeni Aqeeq: Carnelian Stones

Carnelian is chalcedony coloured orange to red by iron oxide. Unlike banded agates, the best carnelian has an even, translucent colour, so light seems to pour through it. Hold a good stone up to the sun and it glows like the heart of a tandoor.

In Pakistan this stone is widely known as Yemeni Aqeeq. The name points to the long trade in carnelian from Yemen, and Yemeni Aqeeq holds a special place in Muslim tradition. Many men wear it in a silver ring, and engraved stones carrying calligraphy are a cherished custom. The name has become a style as much as an origin, and we only state a country of origin when we know it.

Choosing carnelian

• Colour: deep, even orange-red to blood red is most sought after. Pale or patchy orange costs less.
• Translucency: a stone that lets light through evenly looks alive; an opaque, flat red often points to red jasper or dyed material.
• Shape: ovals and rectangles with a flat or slightly domed top suit engraving.

Treatment is common. Much carnelian on the market is agate that has been heated, or dyed and then heated, to deepen the red. Heat-enhanced stones are stable. Dyed stones may show colour concentrated in cracks. Look on each stone's page for its treatment note.

Rated 6.5 to 7 for hardness, carnelian is tough and well suited to a ring worn every day. Its compact structure resists chipping. Wash it with soap and water and dry it before putting it away, so silver around it does not tarnish quickly.