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

You can make 5-8 exchanges per day, depending on the FC level of your state.,
5 refinements unlock with FC 5
6 refinements unlock with War Academy
7 refinements unlock with FC 8
8 refinements unlock with FC10

an exchange costs:
1st refinement :5,000 meat, 5,000 wood, 5,000 coal, 5,000 iron
2nd refinement: 10,000 meat, 10,000 wood, 10,000 coal, 10,000 iron
3rd refinement: 20,000 meat, 20,000 wood, 20,000 coal, 20,000 iron
4th refinement: 30,000 meat, 30,000 wood, 30,000 coal, 30,000 iron
5th refinement: 40,000 meat, 40,000 wood, 40,000 coal, 40,000 iron
6th-8th refinement: 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