I did this on my server for fun, but just thought I would show this. These were all crafted 100% legit, if you watch my let's play, you will see that we have a recycling system set up that can easily generate this kind of scrap. I crafted 18 stacks (minus 2) and just popped em all at once to see how many diamonds I got.
34.
http://www.youtube.com/watch?v=pxVOKYHcVhw
Glad this is being/has been nerfed, but anyway, Enjoy the video!