Neela Topaz: Blue Topaz Gems

Blue topaz is topaz in shades of blue. Natural blue topaz exists but is usually very pale. Almost every vivid blue topaz on the market starts as colourless topaz and is treated with radiation and heat to create a stable blue. This is standard across the world, and reputable treaters hold stones until they meet safety limits before release. You will find the known treatment status on every listing.

Three blues

• Sky blue: light and bright, like a clear March afternoon.
• Swiss blue: vivid, slightly electric mid blue.
• London blue: deep, inky blue with a hint of grey, the most expensive of the three.

Because the colour is created, clarity is usually excellent and sizes are generous. Look for an even colour without patches, a lively cut with no dark window in the centre, and clean, sharp facet edges.

Blue topaz is sometimes offered as a budget substitute for Neelam. It is a completely different mineral. Some families allow substitutes in tradition and many do not, so ask the person who advised you before choosing it for that purpose. As a gift or a fashion stone, it is a cheerful, practical choice.

How does it compare with aquamarine? Aquamarine is a softer sea blue and generally costs more for similar size. Blue topaz is brighter and denser.

Hardness 8 makes it scratch-resistant, but topaz can split along its cleavage plane after a hard knock. A secure bezel or four-claw setting helps. Avoid steam, sudden temperature changes and ultrasonic cleaners. Long exposure to strong sunlight may slowly fade the colour, so store it away from windows.