Princess Charlene's engagement ring features a pear-shaped diamond thought to be between five and six carats, with a platinum band, and it's the most expensive of the European queens' and princesses'.

From sparkling multi-million-dollar diamonds to custom designs, here are the most expensive diamond rings in the world that redefines luxury.

The real kicker here is that this may be her second engagement ring. The tennis pro was spotted with an insane 11-carat, pear ... emerald-cut diamond. Sadly, not even the most expensive engagement ...

From historic heirlooms to custom designs, modern royal women wear some of the most incredible (and expensive ... by three ...