What to do with gems after endless reserves?

Hi,

Just bought endless reserves this round of crab and getting on the USA leaderboard this week hopefully (its jumped up 70vp this month since last crab ugh). What are gems used for now instead of reloading troops when boosted. Crystals into powder?

Please help.

I didn't find the right solution from the Internet.

References:

https://forum.supercell.com/showthread.php/1718424-What-to-do-with-gems-after-endless-reserves