Comments on the picture:
This is just an ordinary shot of an ordinary object.
To make it more interesting, you have to experiment with the lighting to bring out the shine and luster of the diamond. One suggestion is to go to a jewellary shop and look at the display and the lighting used. Study what makes the jewellary so glamourous on the display shelves, and then try to duplicate that.
Another suggestion is to look at jewellary advertisements and brochures for ideas. You might want to set the ring with some decorative objects to compliment (but not outshine) the diamond.
Once you captured the glitter of the diamond, showing the picture in colour may be more interesting.
Hope this helps.