Oh, judging the quality is not to difficult.
Anyone who cuts rocks should be able to do that.
But on the other hand, you'd need a proper ID on the mineral in order to decide if it should be cabbed (cabochon cut) or faceted. The gemmologist should be off help there, to ID your rock.
Amazing specimen. Either aquamarine or emerald, but most likely aquamarine. Maine is known for many gems and beryls of several types can be found in the pegmatites there.