Differences Between Coins, Crystals, Stars and Diamonds
About Coins
Coins could be purchased on Cuddle by going to the "Account" tab - "My Wallet". You could also earn coins by collecting "Check-In Rewards".  
About Stars
Stars only represent the all-time total value of gifts received from other users. 
What are stars used for?
- Star count is only a number and can not be used for anything. E.g. If the all-time total gifts received value of a user is x coin(s), then he/she has the same amount of (which equals to x) all-time total stars. 
 
About Diamonds
Diamonds also represent the value of gifts received from other users. 
How to get diamonds? 
- The coin value of gifts received from other users will be exchanged to diamonds at a certain rate. 
 
What are diamonds used for? 
- Diamonds can be used to cash out.
 
About Crystals
Crystals only represent the account's activity for tasks on Cuddle. 
How to get crystals? 
Crystals can be obtained by completing check-in and daily tasks. 
What are crystals used for? 
Users can send crystal gifts to others in the live room with crystals. Users who receive crystal gifts will get a certain amount of cuddle points to get leveled up.