There are several ways to get rubies:
1. Come regularly to your restaurant and get your daily reward.
2. Build your restaurant, in each new level you will take the opportunity to get rubies.
3. Fulfill missions, you will take the rubies as rewards.
4. Obtain opportunites to see movies by finishing customers' order, after seeing movies, you will get the opportunity of getting rubies.
5. Open the box with field expansion, you will get the opportunity to get the rubies.
6. Buy rubies in app from the game shop.