Can't add Gems

Hi there nancybody​. Are you playing on PC or Mac through either the EA App or Steam. Do you have any mods in your game and have you removed those mods, repaired your game and then checked to see if the issue remains without mods.

nancybody​  Those gems you plant to get the crystal tree don't go in the jewelry crafting station.  You can't make anything with them afaik, but I haven't tried doing that.  The only thing you can do with them is plant them to get the crystal trees.  I have had no trouble with planting them although, I've only planted them in a 2x2 planter in a covered garden.  Usually, if the plant option is greyed out when you try to plant anything, that means it's out of season so you might want to try planting in a covered space.

And as CrispySims619​ said, check your mods to make sure one of them is not causing the problem.  A repair and deleting the localthumbcache file before starting the game next time may help too.  

Hope this helps.