A Rare Bicoloured Yellow and Purple Topaz

Topaz is commonly seen in the gem market, and is usually colourless, yellow, orange, pink or blue; those ranging from orangey yellow to orange to ‘sherry red’ are commonly called ‘Imperial topaz’ in the trade(Sauer et al. 1996). Recently, Guild Gem Laboratories examined an unusual bicoloured topaz weighing 13.01 ct with distinct yellow and purple colour zones (Figure 48a). At first glance it could be mistaken for amethyst-citrine quartz (also known as ametrine).