@samoht04:
The information on the Guide is most certainly correct, but it's also a bit complicated. For me, the easiest way to get a skull cut is to put 8 different cuts of the same gem on the XL Display Case. If I have a Sculptor in the family, I can get the Sculptor's Egg cut gem for much less money than a heart shaped cut and it will be one of the 8 needed cuts. As Carl says in the Guide, you won't really get your money back with a skull cut gem. It's mostly just to have the skull as part of a collection. If your family has plenty of money, it won't matter.
There are other ways to get skull cuts, I'm sure, but this way with 8 different cuts of the same gem is guaranteed to result in a skull cut of that gem. For me, it's worth the expense to know for sure I'll get what I want.