Mounted Gem ID

[beefynerd]

Hey all, new here so my apologies if this isn't the right place for this topic. My grandfather-in-law passed this ring down to me many years ago. I was inclined to post it here in an attempt to identify it, as the closest I've been able to compare it to was a star sapphire, minus the star-shape associated with such a gem. Any ideas? Thank you for your time!