N O V E M B E R

TOPAZ

Topaz occurs in a range of different colours; deep golden yellow topaz (sometimes called sherry topaz) and pink topaz are the most valuable; blue and green stones are also popular. Natural pink stones are rare – most pink topaz is heat-treated yellow material. Much colourless topaz is irradiated and heat-treated to a range of blues, some almost indistinguishable from aquamarine when seen with the naked eye. Some topaz has tear-shaped cavaties, containing a gas bubble or several immiscible (non-mixing) luquids. Other inclusions such as cracks, streaks, and veils also occur. Prismatic topaz crystals have a characteristic lozenge-shaped cross-section and striations parallel to their length. Topaz has one perfect cleavage.