This is a gorgeous green natural emerald that has been part of my personal collection for years. It weighs 2.85 carats. 

It is roundish in the sense that it looks more round than oval, but it's not totally round. It's 10.5mm in its largest area, but slightly over 10mm in other sections. It's flattened on the bottom and would set into a ring perfectly. 

I believe that big it is bezel set it would make it look perfectly round. The color is amazing!!