Amethyst — specimen 0336, photo © NMNHS
Weight: 2.05 ct; size: 8.12 | 8.06 | 5.83 mm; shape: round; colour: medium bluish violet; slightly greyish; clarity: eye clean; cut: good; treatment: none.
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.