Gems are the so-called "premium" currency. You can use it to in Convenient Shop for Special Items, play Fortune Kitty to get Blueprints and Twinkles.
There are 3 main ways to earn gems:
- Pitch challenge result: You can join the Pitch Challenge and submit your best design, everyone will give a vote for you if your design is more amazing than others. When a result comes out, if your design gets 5 stars you will get gems as the reward.
- Rewards Features: You can join Special Event on fanpage (https://www.facebook.com/kawaiihomedesign/) to get gems as the reward.
- Visit the store: Tap on the "+" icon near the Gems icon to buy more Gems for real money. (You can find out how to disable in-app purchases HERE.)