TIP OF THE DAY!!!! Keep your profits higher than your rent, and your production higher than your sales. Don't worry about the gems to begin with. Once you start raking in the dough, click the "cog" button in the top right, and look at "Find a new place for X gems". It doesn't mean what you're thinking! You don't NEED that many gems, you GET that many gems! You start the game over, but now you have a ton of gems to upgrade whatever you want to!
Thank you! We're really happy you enjoyed the game :)