Not exactly. If you have cursed runes in inventory, game forces you to use runes to upgrade and you cannot use gems. Just tested on my acct and confirmed this is still true. You can only spend gems if you use up all your runes , at which point you have no runes to spend on crafting stuff. I didn’t spend 6k gems to upgrade forge on day 1 and have been hoping for a fix so I could use gems over time to upgrade, and save my runes for crafting