This looks like a necklace charm. If you had burried the top end a bit, so that it looked like more of a "discovery" and less like jewelry, it would have improved some. Also, IMO at least, a bit of an angle to it, and different light would have helped. Still though, very cool! 7
I'll start by saying nice choice for this challenge, I really like the medallion. Shadows play nice in this photo and are not overwhelming the main subject. Only thing that is going against you I feel is the color seems a bit off in the sand. Otherwise, good job!