I have looked all over and some people said 500 and that was wrong and I read on a website that 600 was the new diamond but I just hit that today, this is the last thing I need for all diamond then I can move on to ranked finally... does anyone have a hard number?

great mystery i guess. 95 views no answers.

I don't think anyone is specifically looking for when that icon changes from Platinum to Diamond. It's kind of whatever in the general scheme of things - wins alone don't mean much.

The icon indeed does change to Diamond when you hit 600 wins.
I remember paying attention to it when I finally got there.

I'm also pretty positive that it's 600 wins. I was watching a friend's account and saw it switch when it got to 600.