This is some pretty stuff! Identified to me as Idaho Plume, and I wish I had a bucket full of it. Highly defined plumes, with some greenish-blue colored areas towards the bottom. I probably should keep this one...

OK, I gave you two weeks to buy it, so I'm putting it in the collection. You snooze, you lose!

Dimensions: 40mm x 30.5mm x 5.5mm; cab has a flat girdle.  Weight: 53.05 carats.

This cabochon is in my personal collection; it is not available for sale.