At least in photos, Asha looks very realistic. However, it costs so much--you can get nice diamonds (though smaller) for what some of the Asha rings cost, which turns me off.
Before I had a real diamond pendant, I got a .75 from Wink at freecz.com. It really did look realistic. But there's actually a lot of realistic CZ--if it's well-cut, kept clean, well set and under 1 carat, it can be hard to impossible to tell it apart from real diamonds (at least, until it scratches).
But do you have a reason other than price that you don't want a diamond? IN my neighborhood, I find I can get diamonds so reasonably at the local pawn shop that I hav completely given up fakes.
We have a pawn shop thread on these forums--you should look it up.