Sapphire — specimen 0668, photo © NMNHS
Weight: 0.31 ct; size: 5.48 | 2.91 | 1.91 mm; shape: octagon; colour: medium light yellowish green; slightly greyish; clarity: eye clean; cut: excellent; treatment: heating.
Very clean specimen; design ‘Octangulum’ [crown angles changed to 21.00, 18.00], excellent cut by Tan Pen.
More information from ‘Classification’
Most commonly refers to a blue gem variety of corundum, but other coloured varieties of corundum are also described as sapphire, except the natural red.