Star, you could use this picture until you get yours taken. I bet it would stir some interest. You could post a disclaimer too. "This is the Hope Diamond. It looks nothing like the jewelry I'm selling." Then add a smiley face.
Oh you mean you want a good ebay rating. duh? They don't rate in Spice but I'm sure you'll be a great ebayer. A++++ transaction, nice merchandise fast & friendly service. There you go. Just cut and paste it into the feedback.