Natural blue topaz 18.5ct VVS trillion cut loose gemstone for jewelry

Natural Topaz Gemstones

Topaz is an aluminum silicate fluoride mineral (Al2SiO4(F,OH)2) with a Mohs hardness of 8. It occurs naturally as colorless, golden, brown, pink and pale blue crystals, and it is one of the most practical gemstones for jewelry: hard, bright and available in large, clean sizes at modest prices.

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Gemstone guide

Natural Topaz Gemstones

About topaz

Topaz is the birthstone for November, and blue topaz is also a modern birthstone for December. Brazil is the world's main source, and the Ouro Preto region is famous for golden to orange imperial topaz. Natural blue topaz is usually very pale, so the deeper Swiss blue and London blue shades are produced by irradiation and heat. Colorless topaz, often called white topaz, is untreated and makes a bright, affordable stone in its own right.

What you'll find in this collection

All our topaz comes from Brazil. Most stones are blue and irradiated, as described above, and the rest are untreated white topaz, with a few champagne and cognac tones. Cuts include rounds, ovals, marquises, octagons, trillions, cushions, pears, hearts, fancy shapes and briolettes, from about a quarter of a carat to nearly 19 carats, plus a few bead strands. Untreated stones also have their own Untreated Topaz collection.

How to recognise topaz

Topaz is dense for its appearance, about 3.5, so it feels heavier than a quartz of the same size, and it is hard enough to resist scratches from everyday dust. It has one perfect cleavage, running across the length of the crystal, which cutters have to work around. Blue topaz can be confused with aquamarine, but topaz is denser and usually brighter and more saturated.

Caring for topaz

Topaz is hard, but its perfect cleavage means a sharp knock can split it, so choose protective settings for rings. Clean it with warm soapy water and a soft brush, and avoid ultrasonic and steam cleaners and sudden temperature changes. Treated blue topaz keeps its color in normal wear.

Every topaz is natural, and each listing gives its weight, size, origin and treatment, with photos of the actual stone.