I have an emerald target ring that I had made by the very talented David Klass. I have worn it every days for the past two years with no issues what-so-ever. My advice would be to make sure the setting covers the edges of the emeralds. This will protect them from dings and chips. I think your idea to have them set in a target is a great one, but then again...I'm biased.
This is so stunning!!