I really like them! I saw them in person and they are a really nice size- big enough to be a true, chunky cocktail ring, but not so big that you will take out someone's eye if you wave your hand. I like the amethyst a lot- actually I like them all, except maybe the smoky quartz. The price is not terrible either, if you consider the prices of the sugar stacks rings, or how much Tiffany charges for their rings with little diamond chips in them.
I think everyone is right here, they are beautiful! I would like to see them though, the website says they are 9 karats, which sounds really large. But I'm sure you could find something less $$, we are mostly buying the Tiffany name, haha.
I've also been thinking about these rings as I've been searching for a cocktail ring for a long time... I like the Smoky quartz but haven't seen it in person yet. Anyway, I've decided it's not worth it... (even for Tiffany) $800 for sterling silver?!! I'd rather pay a little bit more if it were in white gold but $800 is a bit much for sterling silver! Also, it doesn't look expensive.... it looks like something you'd find easily at those mall jewellery carts.... sorry. But if you don't mind paying for the name then it's a fun piece to have.