Amethyst — specimen 0706, photo © NMNHS
Weight: 0.45 ct; size: 5.71 | 4.97 | 3.55 mm; shape: hexagon; colour: light violetish blue; strong; clarity: eye clean; cut: excellent; treatment: none.
Very clean specimen; design ‘Hexamixtum S 41-32’ [pavilion angle changed to 45.00], excellent cut by Tan Pen.
More information from ‘Classification’
A violet variety of quartz. The colour is caused by iron impurities in the 10s to 100s parts per million range.