Green diamonds are one of the more fascinating of the fancy coloured diamonds. The source of their colouring is entirely unique, and they vary from light green to a deep forest green. The green colour in diamonds is caused when the diamond crystal forms in an area that is exposed to radiation. This radiation is residual, and so these gorgeous and rare gemstones present no harm whatsoever to their wearers. Green diamonds have looked phenomenal set into rings, brooches and various other pieces of jewellery. An intriguing colour, most recorded green diamonds have been bought by diamond collectors and housed in museums.
As with all fancy colour diamonds, green diamonds are graded from a scale of colour intensity, from faint, to fancy dark or vivid. The green colour can also be tinted with secondary hues such as yellow, blue, brown, and grey. Natural green diamonds assume their colour when carbon atoms are displaced from their normal positions through radiation. This happens when the diamond deposits form near to radioactive rocks. This is an incredibly rare phenomenon, and often only affects the outer layer of the diamond crystal, these are known as ‘green skinnned’ diamonds.
As such, green diamonds are typically light in tone and saturation. Often, the green ‘skin’ of the rough crystal is polished off during faceting. A green diamond with a pronounced green body colour is exceptionally rare. Therefore, vivid green diamonds are amongst the rarest and most valuable gemstones around.
As with all of the fancy colours, scientists have been able to mimic the colouring process in green diamonds. In fact, the artificial irradiation used to colour diamonds green is so similar to the natural source, it can be next to impossible for laboratories to determine whether a green diamond is treated or natural. To counter this, most diamond polishers will leave an area of unpolished rough crystal (known as a natural) on the stone to indicate a naturally green diamond.
Without a doubt, the most famous natural green diamond is the Dresden Green Diamond. This diamond is a modified pear-shape brilliant-cut, and weighs approximately 41 carats. It is the largest and finest green diamond to have a colour of natural origin. The historical inventory associated with the Dresden Green helps to prove its natural origin, as its first mention in 1726 far predates modern methods of irradiation methods.