Like RubberSoul was talking about, I've always been on the smaller end of the diamond spectrum... I have really tiny hands, and anything bigger than 3/4 carat looks like a mountain on me.
I actually wear my former engagement ring every day, with my ex-fiance's blessing. (I do wear it on my right hand though, not my left!) It's a gold band with 12 very small diamonds channel set. Not a traditional engagement ring so much, but it's pretty, looks nice on me, and was the best he could afford at the time, which was fine by me.
In the future though.... I want either a 1/2 or 3/4 carat diamond on a gold band...either a solitare with the 6 prong Tiffany set or with the two smaller side diamonds. But really, I'll be happy with whatever I get. I guess I need to get a boyfriend first though, hm?