I'm thinking of putting a "shadow" of the item required on the tables. Basically you put the required items on the tables (which is generally 3 of a kind) and the upgraded item above pops out and you get it. It then quickly reappears and you can get it again as much as you like. I thought this would be a much better system than a convoluted dialogue option with a jeweler. I would have preferred allowing the player to place whatever item they want, but then there's the options and choices and it just gets really complicated (for both me and the player). I think the above setup works best, considering the limitations of the engine. Hopefully I can make a more intuitive combination system in future games. :)