Originally Posted by
Unregistered
Gem are valuable. They take a long time to earn... one for each recipe as you master it. Or you can pay real life money to buy them. The more elite decorations cost gems.
Coins are earned by collecting tips and by customers eating meals. You can also get a daily coin bonus. Coins are easy to get.
IMO I wouldn't use any gems for expanding or for completing recipes early, or anything like that. I wouldn't use them for anything that you can purchase/achieve with coins. I keep my gems for decorations that can only be purchased with gems.