Each of these colour types covers a range, not just a single colour. The appearance of "colour types" is also affected by cutting, clarity, pleochroism and in some cases, fluorescence. All colours are affected by the spectral output distribution (SPD) of the light source used to view them. Certain colours visible to our eyes are not reproducible either in print or on screen. These are termed "out of gamut" colours. Special colour terms will not be awarded for;
This is a vivid blue-violet with a deep tone and is epitomized by the fine sapphires from Burma's Mogok region. In addition to Myanmar, royal blue sapphires are also found in Sri Lanka, Madagascar, Tanzania, Cambodia and Nigeria. Of all the colours of ruby and sapphire, the royal blue is the most difficult to show onscreen or in print, as the colour is out-of-gamut for both printing and most computer monitors.
It is said that a perfect ruby is the same colour as the first two drops of blood drawn from the nose of a killed pigeon. The term is said to have originated from Burma, where locals call the finest and most vivid rubies ko-twe meaning “pigeon's blood”. The pigeon's blood colour is sometimes compared to the colour of a live pigeon's eye. "Pigeon's blood red" is traditionally the term used to describe the finest colours of ruby. It is quite rare to have a stone that is a straight red colour.
Pigeon’s blood colour is a vivid red colour (high intensity and low tone, e.g. no brown, purple and orange overtones) of a certain group of natural rubies. Rubies are medium to strong fluorescence if exposed to UV (365nm) light. Colour is graded in day light and the colour descriptive term GIC colour range - “pigeon’s blood red” is added.
The pigeon’s blood colour graded at GIC could either be heat-treated or unheated.