Royal blue is a trade name for a sapphire of intense, saturated, even blue. It is not a single agreed standard.
In more detail
The term is linked to Burma. Gübelin also gives it to sapphires from other deposits, such as Madagascar and Sri Lanka. Gübelin and SSEF agreed in 2015 to harmonize their criteria, and other labs use their own. Gübelin excludes any treatment, heating included.
On a grading report
Some labs add it as a color term on a report or appendix, each under its own criteria.
Related terms
- Sapphire: Sapphire is corundum of any color other than red. The word alone means a blue stone; other colors take a color word, such as yellow sapphire.
- Pigeon's blood: Pigeon's blood is a trade name for a ruby of intense, saturated, even red. It has no single agreed standard.
- Kashmir sapphire: A Kashmir sapphire is a blue sapphire from the Kashmir region on the India/Pakistan border. 'Kashmir blue' is a trade name for a deep, velvety blue, with no single agreed standard.
- Trade color term: A trade color term is a market name for a fine color, such as pigeon's blood, royal blue or cornflower. It is not a gemological standard.
- Saturation: Saturation is the strength or purity of a gem's color, from grayish or brownish to vivid.