The world's main source of authentic topaz are the states of Minas Gerais and Ouro Preto in Brazil, though it is also found in Australia, Burma, Ukraine, U.S, Pakistan, Afghanistan, Mexico and Sri Lanka. It is a very hardy and heavy stone, rated 7.5-8.5 on the Moh scale, and it is extremely durable over time. Typically found in clear, lovely shades of brown, topaz can be either the famous pale yellow or orange-brown, amber and even pink-brown and red. It is also found in shades of blue, pale green, yellow-green, violet or in a colorless variety. It is normally light brown when mined but the color fades very quickly if exposed to light or even low heat. Brown and blue are the most typical varieties, so yellow, orange or pink shades are highly regarded and very valuable.
The most prized topaz is the golden yellow or pale orange variety that is often called ‘Imperial topaz' or ‘Precious topaz'. Intense colors with pink overtones can cost anywhere in the market of $150 to $2500 per carat weight and even more. The set prices are $125-$1800 per carat for gems less than 3 carats and $190-$1700 for gems of 4 or 5 carat weights. However this isn't the most expensive kind- very high quality, authentic deep pink or red topaz from Pakistan costs the most, with the most saturated gems bringing in the highest prices. The market is flooded with so-called ‘red' topaz, but almost all pink or red topaz is a brownish-yellow variety found in Brazil and heat-treated to change
Authentic, untreated topaz is very difficult to find these days, even with a lot of money to spend. It has become very popular to treat topaz and to sell anything that remotely resembles it as the real item. It is routinely heat-treated and diffusion-treated and even radiation-treated to deepen or change color and remove inclusions. It is itself used as a substitute for even more expensive and rare gems such as the fine blue aquamarine. Green and blue topaz do occur naturally and very frequently but they are also almost universally treated with radiation and have subsequently lost almost all market value these days, retailing at less than $20 per carat weight. The usual price range for blue gems is $5-$15 per carat for gems less than 5 carats and $10-$25 for gems of 5-20 carat weight.
Blue topaz has flooded the market and today all blue topaz in the U.S is automatically tested for radiation levels. There are also too many imitations to count and anything called “Madiera topaz”, “Smokey topaz”, “Scottish topaz”, “Occidental topaz”, “Saffranite topaz”, “Spanish topaz”, “Palmeira topaz” or “Rio topaz” are all types of citrine and certainly not real topaz.