Loads of JPeg artifacts is an instant turn off for me.. also the pendant seems to be hidden behind a haze of sorts possibly because of the light source off to the left :(
Nicely done. Simple and bold, the background enhances the image. A good photo that would help to sell this item online.
There are a lot of JPEG compression artifacts showing in this image, especially around the chain. When I looked at the size of the image file, I knew why. It is only 32k in size. You can save with a lower compression ratio and solve that problem. For challenges, it is best to choose the compression ratio that will get you as close as possible to the 150k size limit, but still under it. Hope this all helps some.
The misty look here is not quite attractive. Maybe it doesn't have enough contrast in it? A little careful editing could bring out more detail in the piece. Lovely pendant though!