Topaz Description

This selection of gems from Ouro Prêto, Brazil and Russia's Ural Mountains, displays the golden orange to pinkish red colour range of precious topaz. The gems range from 7.61 to 14.33 carats in size.
Many consumers know topaz as simply an inexpensive blue gem. They’re surprised to learn that its blue colour is hardly ever natural: It’s almost always caused by treatment. They might also be surprised to know that topaz has so many more colours to offer gem lovers, including pinks and purples that rival the finest fancy sapphires.

Reddish purple pear-shaped topaz
This superb reddish purple pear-shaped topaz from Brazil's Capão mine displays the gem’s top colour. - Courtesy Dr. Wagner Colombarolli
Topaz is allochromatic, which means that its colour is caused by impurity elements or defects in its crystal structure rather than by an element of its basic chemical composition. The element chromium causes natural pink, red and violet-to-purple colours in topaz. Imperfections at the atomic level in topaz crystal structure can cause yellow, brown and blue colour. Brown is a common topaz colour, and the gem is sometimes mistakenly called “smoky quartz”.

Imperial topaz
So far, commercial deposits of imperial topaz are found in a single area of the world: Ouro Prêto in Brazil. The 6.00-carat pear shape and 3.82-carat antique cut display nuances of the gem's colour. - Courtesy Suwa & Son
Topaz crystal
Against the light, this crystal's colour zones and high clarity stand out clearly. It might be possible to fashion a unique gem from this piece. - Courtesy Dr. Wagner Colombarolli
Topaz actually has an exceptionally wide colour range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and purple. Colourless topaz is plentiful, and is often treated to give it a blue colour.

Topaz crystals
Topaz crystals are typically elongated, with grooves parallel to their lengths. For this reason, they're commonly cut into long oval or pear shapes. These crystals show orange, pink and brown colours. - Eric Welch/GIA
The colour varieties are often identified simply by hue name—blue topaz, pink topaz and so forth—but there are also a couple of special trade names. Imperial topaz is a medium reddish orange to orange-red. This is one of the gem’s most expensive colours. Sherry topaz—named after the sherry wine—is a yellowish brown or brownish yellow to orange. Stones in this colour range are often called precious topaz to help distinguish them from the similarly coloured but less expensive citrine and smoky quartz.

Topaz is also pleochroic, meaning that the gem can show different colours in different crystal directions.