As already mentioned, true or yellow topaz may be pinkish orange or yellow with a pink tinge. There is in fact a whole range of color gradations from yellow to pink, and it is hard to establish a dividing line between the two varieties.
Appearance In some cases the color is pink with a distinctive yellowish or orange shade, but it is more often a definite light to medium pink, tending to red or violet in deeper colored stones. The color is not always evenly distributed and can show slight crystallographic zoning. The stones usually have few inclusions and are strongly transparent and lustrous.
The most common cut is the oval or pear shape, but many other old or antique faceted cuts are seen, as is the step cut. While it has always been comparatively rare, pink topaz was much appreciated in antique jewelry and stones weighing up to 10 carats are often found.
Distinctive features At first sight, there is not a lot of difference between pink topaz, kunzite, morganite, and some pink tourmalines. But a density test with a heavy liquid such as methylene iodide, in which topaz sinks but the others float, will distinguish ‘topaz from the others. It is harder to tell pink topaz apart from pink spinel and pink corundum, the former having about the same density as topaz, and the latter having a higher density. In case of confusion with these stones, other properties, such as the refractive indices, need to be examined.
Occurrence Pink topaz comes mainly from Brazil, but has also been mined recently in the Ural mountains of the Soviet Union. In both places, intensely colored reddish or purplish specimens have very occasionally been found.
Value When the color is fairly intense, it is one of the most valuable of the second level of gemstones (e.g. aquamarine). Specimens that are too pale have a low value. Like yellow topaz, it was perhaps more highly prized in the past than today. _
Simulants and synthetics At one time glass imitations were occasionally produced. In. antique jewelry, very pale stones were sometimes given a closed setting with a painted base to heighten their color.
The pink color of many topazes is due to heat treatment of pinkish-yellow stones from Brazil. This method goes back at least several centuries, so even antique stones may have been“colored in this way. This procedure, however, has always been regarded as admissible in the gem trade, so the question of whether the color of pink topaz is natural or due to heat treatment does not arise.