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Outshining Gold: Imperial Topaz Rough from The Black Gold City

By Alissa Young, GG

On behalf of Milstead Gems LLC


The city of Ouro Preto, meaning Black Gold, was named for the rich wealth of gold hidden within black rock in the former capital of Minas Gerais, Brazil. A UNESCO World Heritage site, Ouro Preto played a central role in the Brazilian golden age and gold rush in the eighteenth century, its Baroque buildings hosting artists and revolutionaries alike.(1) Today, the remote region is better known for another hidden treasure: imperial topaz rough.

imperial topaz rough, Ouro Preto Topaz facet rough
Imperial Topaz Rough from Ouro Preto

Like gold, imperial topaz is often associated with the color yellow. However, topaz in its purest state is in fact colorless; traces of chromium create pink, red, and violet to purple hues, while defects in the gem’s crystal structure result in yellows, browns, and blues. When both chromium and color centers are present, they can create a lovely orange imperial topaz.(2) The many vivid shades of topaz each have their own evocative names to describe their rich colors, including the rare and coveted precious and imperial topaz rough varieties that Ouro Preto is renowned for.


Although there is some debate as to where imperial topaz rough earned its moniker, its history is always linked with royalty. One theory holds that the name originated in Russia, where stunning pink topaz was found within the Ural Mountains in the eighteenth century. The Russian tsar was said to have been so captivated by the vibrant gem that only he and his family were permitted to wear them.(3) Another version, however, links the name to a different monarch. When Portuguese Emperor Peter II visited Ouro Preto in 1881, he allegedly received a reddish topaz from prominent French mineralist Henri Gorceix.(4) In his honor, all topaz with a red hue was referred to as “imperial.” No matter who is credited with naming the prized gemstone, however, one thing remains the same: imperial topaz was fit for royalty.


While the history of the imperial name remains disputed, what qualifies as “imperial topaz rough” is perhaps even more contested. The Gemological Institute of America defines it as “gem-quality topaz of medium reddish orange to orange-red color.” Traditional traders often require imperial topaz to have a red component, whether it is the dominant hue or present in pleochroism along the length of a yellow or orange crystal. In recent years, imperial has been used to describe a broad range of topaz colors, from golden yellow and orange to peachy pink and lavender.(5) Golden and yellow topaz without a red component is also referred to as “precious,” a nod to their desirability and value. When these gems display the warm brown overtone of a glass of aged white wine, they are aptly named sherry topaz.

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Collection of Imperial Topaz Rough from Milstead Gemstones

Although the beautiful stone can be found in small quantities in regions like Russia and Pakistan, Brazil remains the most important source of gem-quality topaz. Some of the finest specimens of precious and imperial topaz rough can be found in the verdant hills of the Vila Rica, or Rich Valley, of Ouro Preto. While a majority of the material is produced in the Capão and Vermelhão mines, the region also hosts many independent artisanal miners known as “Garimpeiros.”(6) Mining operations large and small search through weathered host rocks to find the elusive topaz crystals the region is renowned for. Formed in the orthorhombic crystal system, topaz is commonly found as long, striated crystals ideal for longer oval, pear, and emerald cuts. Gorgeous natural red, pink, orange and yellow gems are unearthed from these mines to be sold around the globe.(7) The more plentiful light and less saturated topaz stones have their own market, and are often treated to improve their color. Natural blue topaz, for example, is very uncommon, but can be produced by irradiating and heating colorless topaz. Some specimens of