I try to give golem a gem after unlocking gem golem, but if i have stack of 4 rubies, it will give him all 4 rubies, and i don't know how give him only 1, without doing some weird things like droping or transmorgify gems
Seconded. The only way to get around this is to drop/transfer all of the kind of gem you want to use and then extract them from metal until you get one of the kind you want. Then equip the golem with this one and repeat. Otherwise you have to actually buy gems.
While it is not really that bad, it is annoying. you have to drop all but 2 gems, move a space, drop then drop a single gem. After this, equip the gem you have left, then pick up the other and give it to the Golem. After this, you can pick up the remaining stack.
It's certainly annoying. A slighty quicker workaround is to drop one of each gem you want to insert ( i -> click -> select 'drop' ). Then move off the gems and press F2 to become your golem and walk over the gems to pick them up, then hit i as normal to equip them. Hit F1 to return control to your alchemist.