Look at making it a bit more eCommerce-orientated.
It needs an area with checkout's and maybe a login/register for people who are interested in updates about new products and saving their shopping cart etc.
The home page gives very little information as well, and although it looks OK, it is essentially just one large image and a title and that's it.
You need to add a description, even just a paragraph, about what your comapny is/does.
Also, some contact info on the home page is always a winner for more contact from customers. Although a 'contact us' section is good, a phone number or email address on the home page helps a lot.
And ouch on the prices. I couldn't afford these items if my life depended on it
I liked the site and loved the jewelry! Only two things about the site bothered me. The first was that it seemed very slow to load, but I guess that's the price of high quality graphics. The other was the left and right buttons on the lightbox. In a site devoted to luxury and elegance, those buttons seemed out of place.
Everything about the site and the its product was excellent.
I think the jewelry pieces looks very good on the black background. one thing I need to say. I would change the font of the horizontal-top menu to Arial. I think it will make the store looks more professional.