Pink, perhaps with exception of blue, is arguably the most commercially (as opposed to naturally) rare diamond colour today. In diamonds, this most feminine of colours is due to selective absorption of the green wavelength (at 563Nm) of visible light. The reason is mostly post-growth plastic deformation inflicted by crumpling and slippage of the crystal lattice causing the colour to be concentrated as pink lamellae. Hence colouration in pinks is often uneven. These ‘grain lines’ as they are called are commonly indicated on the surface of the rough. The nature of these structural defects is very similar to those in brown diamonds. Generally, the more numerous and tighter the pink graining, the more deformation has been experienced by a diamond and the stronger its colour becomes. These structural ‘defects’ also increase inner tension and diamond cutters are well aware that pink stones are more susceptible to shatter on the polishing Scaife.
Type IIa pinks usually either show a soft, pure pink or an orangy to brownish modified Pink. Purplish is only rarely seen in such stones. They are characterised by a warm tone and commonly feature faint to medium blue fluorescence. Some old Golconda Pink may also fluoresce an atypical orange. Although they may rarely be hazy they are distinctly devoid of inclusions.
Type I pinks which represent approximately 70 to 80% of all pink diamonds tend to be the more strongly coloured.
In the famous Australian Argyle intense to vivid purplish pinks the cooler hues are caused by a complex colour centre which involves isolated nitrogen atoms coupled with atomic vacancies and trapped chlorine atoms concentrating colour along parallel slip planes. A resultant absorption line at 550Nm leads to a more purplish bodycolour. Purplish pink diamonds are also notably more zoned than pure pink stones and Argyle stones, in particular, are rarely cleaner than Si1 grade.
Furthermore, fluorescence in Type I pinks is rather uncommon.
With the exception of rare and highly desired reddish pink stones, the most coveted classic hues are baby to bubble gum pink followed very closely by purplish Pink and Purple-Pink. Although pure Pink is a slightly different colour, purplish adds richness to such diamonds making them at times more appealing. These aforementioned hues are followed in popularity by orangy Pink and Orange-Pink which may resemble ‘old rose’, salmon or apricot. However orange and brown in particular may not easily be distinguished, hence orangy Pink diamonds ought to be carefully chosen. True brownish Pink and Brown-Pink are by far the least appreciated of all pinks and are rather priced at a premium to usual brown diamonds.
The most valued saturation levels in pink diamonds are vividly followed by both intense and deep.
To reinforce their colour pink stones are often mounted in rose or red gold.
Pinks diamonds are currently mined at the Australian Argyle Mine, the Williamson Mine (Mwadui) of Tanzania, in South Africa, Angola, Lesotho, Sierra Leone and Liberia as well as Russia, Brazil (Minas Gerais region) and Canada.