Help assess this 10mm amethyst

[Slickk]

Hi all, so I found this 10 mm deep purple round amethyst stone in my mother's "treasure chest." She passed away and I do not know what this is worth or if I should have it set or sell it. Any ideas on how I go about finding out about this stone's value. A colleague (ex jeweler) said this is real and very well cut. Any suggestions on how to research? Thanks all!

 

[chrono]

Amethyst are generally inexpensive and a 10 mm stone as shown will retail around $150 brand new, with a secondhand price of $50 to $100 at best.

 

[JewelFreak]

Why not have it set in a ring & wear it? It's pretty.