I was at Nordies today trying on chunky cocktail rings, they were all size 7. That's my pinky. My middle and ring fingers are about a size 10.
Unless it's custom I never find sizes big enough, unless they are men's.
I would love something like this:

http://www.net-a-porter.com/product/162059

I used to have a gorgeous moonstone and silver ring that my mother bought me, but I lost in a move.