The Supernatural expansion pack added a machine that would let sims cut gems at no cost – the gem cutting machine. While it did take the sim through the progression of different cuts from the most basic emerald cut through the moon cut (even the expensive heart cut is there, but it seems to be available right from the beginning of a sim’s use of the machine), the gem cutting machine did not impose any simoleon charge to cut the gems, unlike sending gems away to the gem cutter via the mailbox.
If your sim can’t afford to purchase one outright, head over to the elixir consignment store. There’s a gem cutting machine there that your sim can use for free. The machine is quite loud and will wake other sims in the house, even if they are separated from the machine by several floors. Sims with the heavy sleeper trait may be able to sleep through the noise, but everyone else, including Bonehilda, will be awakened by its noise, and you may see one or more of your sim’s family members come down to complain about the noise.
One other thing I noticed with the machine has to do with a sim’s want list. When you see this want appear in a sim’s list:
Your first thought might be that as long as you get a gem cut with the machine, it should satisfy this want, right? Well, it isn’t quite that simple. You see, in order to satisfy this want, you have to click on the gem cutting machine and select “Cut a stack of gems…” then follow the dialogs to select a gem type and cut. If you click on a gem in your sim’s inventory and select “Cut [all] with machine…”, your sim will still use the machine and cut the gems, but it won’t satisfy this want. Starting the interaction from the gem cutting machine is the only way that I’ve seen so far to satisfy the want.
But if this want does appear, it’s an especially quick and simple way to add 200 lifetime happiness points to your sim’s balance. It’s not a lot, but it adds points faster than just letting your sim be happy.