Violet, a pure colour by itself is visually placed between Blue and Purple with violet diamonds tending notably towards the Blue. In the visible light, spectrum violet is found at the end between blue and ultraviolet.
Violet in diamonds is often perceived as a secondary hue, accompanying Grey to Blue primary colours. Violet diamonds are amongst the rarest of fancy colour diamonds. They occur mostly as Type 1a diamonds and rarely as Type IIb. Their colour origin is thought to be found in hydrogen-related defects. Some stones are also known to contain minute amounts of boron.
The colour is caused by absorption in the deep red range at 550Nm and 600Nm, similar to greyish blue stones from the Australian Argyle mine.
Most violet diamonds come from Russian deposits, the Argyle Mine and less commonly the Republic of South Africa.