Blue John – Rhomboid Cut

Description

Blue John – Rhomboid Cut 20.29 Carats .       26.1 x 11.8  mm

Blue John is a semi-precious mineral, a form of fluorite with bands of a purple-blue or yellowish color. In the UK it is found only at Blue John Cavern and Treak Cliff Cavern at Castleton in Derbyshire.