In the crystal laboratory, you can exchange resources for fire crystals every day.

You can make 7 exchanges per day, an exchange costs:
5,000 meat, 5,000 wood, 5,000 coal, 5,000 iron
10,000 meat, 10,000 wood, 10,000 coal, 10,000 iron
20,000 meat, 20,000 wood, 20,000 coal, 20,000 iron
30,000 meat, 30,000 wood, 30,000 coal, 30,000 iron
40,000 meat, 40,000 wood, 40,000 coal, 40,000 iron
50,000 meat, 50,000 wood, 50,000 coal, 50,000 iron
50,000 meat, 50,000 wood, 50,000 coal, 50,000 iron

Each exchange can give between 1 and 5 fire crystals, with the following chance rate:
- 1 : 40%
- 2 : 30%
- 3 : 15%
- 4 : 10%
- 5 : 5%

Once your state unlocks FC6-8 you can perform super refinements. You can read more about super refinements here