Black diamonds are opaque fancy-color diamonds ... making it one of the most expensive rings in the entire world. Pink diamonds are another form of fancy-color diamonds. Experts disagree about ...

This $500,000 heirloom might not be the most expensive ring on the list, but it's sentimental value is worth so much more. Princess Diana also wore this ring while she was engaged to Prince Charles.

The jewellery experts at 77 Diamonds recently took a look at the rings of the women in the European royal families, ranking them from most to least expensive, and the results may shock you.