The following is an excerpt from GIA’s article on Potentate’s “Montana Queen” sapphire.

In September 2016, while viewing a selection of large Montana sapphires mined by Potentate Mining at their new operation at Rock Creek, one stone stood out. It possessed a beautiful medium blue-green color and a hexagonal crystal form with a blue rim and golden center (figure 1). It weighed 31.98 ct (6.40 g) and appeared to be free of major internal defects. Sapphires this large make up less than 0.25% of Rock Creek’s production, and they are typically fractured or otherwise included.

Read the full article:

https://www.gia.edu/gems-gemology/fall-2017-gemnews-montana-queen-sapphire