Labradorite is the name given to a gem variety of feldspar. It displays labradorescence – a shiller effect in lustrous metallic tints, often blue and green, sometimes purples, oranges, and reds or any combination of all these colours to brilliant effect. It has a specific gravity 2.56 to 2.60. Monoclinic crystal system and a hardness 6-6.5 on the Mohs scale. It needs to be cut on a 30 degree angel to the grain to the stone in order to show its colour, so usually only one face will display the play of light or flash of colour.