Also, before the gem-cutting machine, your Sim could send gems in the mail to be cut. The gem-cutting machine is free, whereas the mail option (which is still available) cost 10 simoleons for the emerald cut, and went up in price from that. If you click on the gem, and click on "cut" rather than "cut with machine", it will go through the mail, just like the metals when you send them off to make ingots.