Pigeon's blood is a trade name for a ruby of intense, saturated, even red. It has no single agreed standard.
In more detail
The term once described fine rubies from Mogok, Burma. Gübelin and SSEF agreed in 2015 to harmonize their criteria, but interpretations still differ. Gübelin also asks for strong fluorescence and excludes any treatment, heating included. Other labs that use the term set their own criteria.
On a grading report
Some labs add it as a color term on a report or appendix, each under its own criteria.
Related terms
- Ruby: Ruby is the red variety of the mineral corundum. Chromium causes its red color.
- Royal blue: Royal blue is a trade name for a sapphire of intense, saturated, even blue. It is not a 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.
- Fluorescence: Fluorescence is visible light, almost always blue, that some diamonds give off while ultraviolet light shines on them. It stops when the UV goes off.
- Saturation: Saturation is the strength or purity of a gem's color, from grayish or brownish to vivid.