Topaz

Topaz is one of the hardest and brightest gems in this guide. A well-cut topaz throws light back at you from every facet, the way the desert does at midday.

Namibian topaz comes from the Erongo region, where it grows as clear, colourless crystals, sold in the trade as "silver" topaz. Most people know topaz as a vivid sky-blue or deep "London" blue. Those colours are real topaz too, but they are created by treatment, and we think you should know exactly how.

What it is

Topaz is an aluminium silicate that contains fluorine. It forms in granite pegmatites and in cavities in volcanic rock, sometimes as very large, perfectly shaped crystals. Natural colours range from colourless and pale blue to sherry-gold, pink and, rarely, the warm orange called imperial topaz.

Beliefs and legends

• The sun god's stone. In ancient Egypt, topaz was linked with Ra, the sun god.
• Strength. The ancient Greeks believed topaz gave them strength.
• Against spells and anger. In Renaissance Europe it was thought to break magic spells and calm anger.
• Worn above the heart. In India, topaz worn above the heart was said to bring long life, beauty and intelligence.
• Fit for a tsar. The pink-orange "imperial" topaz of Russia's Ural Mountains was named in honour of the tsar, and only the royal family was allowed to own it.

Treatments, honestly

Almost all blue topaz started life colourless. It is irradiated and then heated, which turns it a stable, permanent blue. The process is safe, widely used and fully accepted, and it is why blue topaz is so affordable. A natural, untreated colourless topaz is a different thing: quieter, and entirely as the earth made it. We tell you which is which on every piece.

How to judge a topaz

• Know what you are buying. Natural colourless or pale stones and treated blues are both good choices. They are priced differently, so ask which one you are looking at.
• Look for brilliance. Topaz should sparkle across its whole face. A dull or "windowed" centre means a shallow cut.
• Expect it to be clean. Most gem topaz is free of inclusions you can see with the eye.
• Warm colours are the rarest. Natural pink and imperial orange topaz cost far more than blue.

Caring for your topaz

Topaz is very hard (8 on the Mohs scale), so it resists scratches well, but it has one weakness: it splits more easily in one direction, and a hard blow can split it. Wear it every day, but take rings off for heavy work. Clean it in warm soapy water with a soft brush. Avoid ultrasonic and steam cleaners and sudden heat.

At a glance

Mineral	Topaz (aluminium silicate)
Hardness	8 Mohs; can split along one direction
Colours	Colourless ("silver"); treated sky to deep blue; rarely gold, pink, orange
From	The Erongo region, Namibia
Treatments	Blue topaz: irradiated and heated (permanent). Disclosed per stone
Care	Warm soapy water, soft brush. No ultrasonic, no hard knocks