Hmmm...
Maybe like the Minecraft inventory, where you could hold 36 (The minecraft inventory is 4 units tall and 9 units long) stacks of 64 items (or 2304 gems) in your inventory. Then you would have a bank where you could store more... Say something like 8 high by 12 long grid in a "Vault". AKA that would be up to 6144 gems in one vault, and up to 6 vaults in a bank cell. That adds up to about 39 thouzand gems in total you can have at one time. That's a hell of a lot, Isn't it? BTW< You'll want to make it so you can sell the gems or something if you haven't already.
Sorry for the bump. I also want to see your progress. A lot.