challenge -- met. nice title btw. technical -- you did well controlling reflections that are so easy to get in these kind of pictures. the beads on the chain to the left are just a tad soft, but not very distracting, so i wouldn't worry too much about it. composition -- i am puzzled what made you use the gems as a background. overall it makes the image very busy IMO. did you try taking a pic of the chain actually around your neck with your skin as the background? i know that's a totally different picture, but (for me) that would tie the background in more with the subject. you have a decent picture regardless.
Background seems distracting. There are almost two pictures here---the locket and chain being one and the "blobs" being another. It might have been an idea to separate the two---each could stand on its own but they don't really seem to work together. Nice clarity.
good composition, great mix of colors, would be even nicer if the face of the pendant was a tad more in focus... oh and the pendant looks like if it was on a silver chain it would make a nice gift :o)