Pigeon's blood

A trade term for the most saturated pure red in ruby, historically tied to fine Mogok material whose strong fluorescence makes the colour appear lit from within. Several laboratories now grant the term under written criteria; they differ on the exact boundaries and on whether stones from outside Burma qualify. It describes colour alone. Treatment and origin are separate lines on the report, and the premium the phrase commands belongs only to stones where a named laboratory has put it in writing.