I like the luster of the gemstone, but the metallic texture of the blade seem lost completely - it looks more like wood. This might need a second light or a reflector to bring out the details of the dual subject.
This picture has potential but there are a few things that affect its overall effect. It looks a little slanted to the left. It is too flat ie. no feeling of depth. The picture would have been more interesting if the gem were not directly in the center of the picture. The green backround is OK but where is the yellow in the gem coming from?