Few gemstones carry as much history as turquoise. Egyptian artisans wore it. Persian miners dug it out of the mountains. Navajo silversmiths built a whole visual language around it. And today it sits on stacked rings and dainty pendants worn to the office on a Tuesday.

Turquoise has a character that's difficult to mistake. Its blue-green colour, natural variations and distinctive matrix can make even a simple piece of jewellery feel individual. But appearance alone doesn't tell you whether you're looking at genuine turquoise, treated turquoise or an imitation.