Guilds - gold and gems in the treasury

[Gambit]

My guild master asked if I would post this question. 

While you can see that gold allows you to increase both administration and stash size, what are gems used for after donation?  I am reluctant to donate without knowing if they are useful as he has not figured out how to remove anything put in the treasury.

That is the next question - as guild master can he remove gold or gems from the treasury or just spend it on upgrades?

I did look for guidance under both News and Guilds but did not see any posts on this topic.

Gambit

[radooo]

You can not remove gold or diamonds from treasury. And diamonds are used for later upgrades of administration and stash size (after the 9k gold upgrade)