Got this on ebay, and I'm not wowed, but haven't cleaned the stones yet either. It was sold as .75ctw but looks small to me for that. I haven't measured closely yet. Just eyeballing against a mm ruler they seem to be 4mm diameter, which would be a bit less I think!
If you combine them with the other pair of eyes you got, you could put a smaller one and a larger one side by side with the post under the smaller one, or do danglies with the larger ones dangling.
He he he...So glad someone else said that before I did. Definitely like the "other" ring much better. The stones that is. Those diamonds need to be released of their home.