Grey skies, grey days and……grey diamonds?
Most of you will have heard of colourless diamonds, black diamonds, yellow diamonds and maybe even pink diamonds. However what about grey diamonds, and why have they boomed in popularity in recent years?
Grey diamonds are somewhat of an enigma. Considered beautiful by many, grey diamonds are rare, mysterious and often misunderstood.
So what are grey diamonds?
Grey diamonds are typically natural diamonds that through trace minerals and structural defects effect a grey colouration. Typically many grey diamonds contain a high level of hydrogen as an impurity element, which can also add to their colouration.
How are they formed?
Grey diamonds obtain their colour in 3 main ways:
Typically the presence of the trace element Boron in diamonds leads to a blue colouration.
It has been noted that some grey diamonds typically arise from a combination of blue boron and structural defects that effect light absorption. This combination can create a colour that we see to the naked eye as grey.
This defect in the diamond structure has been known and studied for decades, however very little is still known about how the hydrogen impurities affect diamond colour. Nevertheless, diamonds exhibiting this defect typically display a grey colour.
Micro inclusions and cloud like features can cause a grey colour in diamonds.
There is a lot of research still ongoing into these micro inclusions and indeed a recent study identified graphite inclusions in several mixed-habitat research diamonds. This means that many grey diamonds may indeed receive their grey colour due to the presence of graphite micro-inclusions.
There are many other possible ways that a diamond can take on a grey colour. Research is ongoing
and interesting studies are being carried out that will hopefully provide more clarity on grey diamonds.
Do grey diamonds come in different shades?
Grey diamonds come in the following intensity levels:
Light Grey, Fancy Light Grey, Fancy Grey, Fancy Dark Grey, and Fancy Deep Grey.
Popular marketing terms for grey colour diamonds include charcoal grey, steel, pigeon, slate, silver, chrome grey and many others. No two diamonds are the same and many grey diamonds will showcase another secondary colour like grey-blue, grey-violet etc. Such diamonds are often among the most desirable and valuable.
Where are grey diamonds mined?
Natural grey diamonds are most frequently mined in South Africa, India, Russia, Brazil, and Australia. The latter is home to the famous Argyle diamond mine. Best known for pink and brown diamonds, Argyle yields diamonds of many colours, including grey, which accounts for roughly 2% of the mine’s coloured diamonds. Most blue-grey diamonds from Argyle are classed a Type Ia, meaning they feature large concentrations of hydrogen and nitrogen defects.
Are grey diamonds expensive?
Grey diamonds tend to be quite a bit less expensive than their colourless and fancy-coloured cousins. Despite their rarity, they’re still relatively affordable, however in the more rare colours, especially stones with a secondary modifying colour they can become extremely expensive.
Why are they only popular as of late?
Until about 2010, there was not much demand for grey diamonds. The colour was often seen as undesirable however this changed when designers started using them in jewellery. This came about largely due to the fact that in late 2009, mining giant Rio Tinto rolled out a line of silvery-grey diamonds called Silvermist. These stones were priced at up to 40% less than colourless diamonds and designers started to see use for them in their designs. This started a shift in the perception of grey diamonds and they began to gain in popularity. Today they are in demand and perfect for those looking for something a little less pervasive than a classic solitaire engagement ring.
Some interesting facts about grey diamonds….
- Most grey diamonds, like blue diamonds, are semiconductors of electricity. The majority of colourless diamonds are non-conductors.
- Some grey diamonds that have boron present in their structure exhibit visible phosphorescence. This means that the diamond glows in the dark for a short period of time. The world renowned Hope Diamond for example glows a stunning orange-red for up to one minute in the dark. The glow is thought to be caused by an interaction between ultraviolet light, boron and nitrogen present within the structure of the diamond.
- Some of the most famous blue diamonds in the world have official colour designations of “Grayish Blue”. The famous Hope Diamond, the Sultan of Morocco, and the Wittelsbach diamond all have a secondary grey colour designation.