Where to get this ring?

The pic is from the November French Vogue.
The ring is from Dior Jewelry, don't know which collection (I guess Spring 2009)



--> better pic http://4.bp.blogspot.com/_iVI9yA76FSs/STzI9HNx-TI/AAAAAAAAKLw/kV7lPeuWn-A/s1600-h/Adriana+Lima3.jpg

--> features the specs of the outfit (look for "bague" french for ring), it's the second outfit listed