Well, if you don't care about what the gem outcome will be, just be sure to have 5 different cuts. But some people love a certain gem or such and maybe want a soulpeace skull cut, so having 8 soulpeace gem cuts will give the 100% gem type you want. The best way to find gems for me was the space rock breaking from the boards, which works for the "collect" option and after ten gems you can get the heart cut. For some reason the Drill never did this, but the rock usually got me 3 - 7 gems before fatigue, and with the moodlet manager you can take it off and start right away again. The gem crafting does get quite addicting though, lol.