Ruby — specimen 0318, photo © NMNHS
Weight: 0.11 ct; size: 2.67 | 2.63 | 2.00 mm; shape: round; colour: medium dark purple; strong; clarity: eye clean; cut: good; treatment: heating.
Small, very clean specimen; good brilliant style cut. Source: David Weinberg, Multicolour Gems Ltd
More information from ‘Classification’
A red, gem variety of corundum. The red colour is caused by minor amounts of trivalent chromium replacing aluminium in the crystal structure.