MAF is right, though. It's easier on a PC because the screen is huge. There is also a safe guard in place as you have to click the gem, then move it. It's not just a matter of drag and drop. Harder to do on a tiny DS screen, and I haven't played it all, so it may have just broken controls from the start.
The truth is, even with the PC, I like controlling it better on the PSP.