|The Medusa emerald|
The Medusa Emerald is one of the world’s finest mineral specimens, having been hidden for millions of years in a huge bolder of quartz. The Natural History Museum in London now has it on display, the first time in Europe, and it's a unique Emerald. It is unusually large with high clarity and intense, strong colouring and is more like eight Emerald sticks protruding from a bed of quartz rock.
Its owners, Gemfields, used state-of-the-art techniques to reveal it, millimetre by millimetre, cutting it from the rock to reveal the beautiful emerald crystals within, a labour that took several months by the world's specialists.
Writing The Emerald Killers began my fascination with emeralds. I used the notorious Boyaca Emerald Valley in Colombia as a backdrop for my thriller about the illegal trade in emeralds there. I also discovered that the green gemstones should not exist at all. A quirk of nature millennia ago brought chromium and vanadium from another continent across the world, trapped in the earth’s moving tectonic plates, to fuse with clear beryllium, creating the lustre of the intense green colouring.
Emerald is twenty times more rare than diamond and sells at the same price per carat. Its specific gravity being low any emerald is larger per carat than other gems. If you hold an emerald to the sun you will see its fine ‘garden of inclusions,’ a tracery of tiny chambers trapping the gases of its creation within it. These do not detract from the price.
These ‘inclusions’ are sealed with palm or cedar wood oil before it’s sold. In my book they are smuggled out of Colombia to New York and legitimised into the gem trade.
The Medusa is on display at the Natural History Museum for 12 months.