I've tried brute forcing the gems without any bird hints and trust me ain't no fun lol. But at some point the sunk cost fallacy is just too much so I had to find a calculator to list me all the combos and try them one by one... all so I can get some walnuts earlier...
I think RoseNoire summarized it well but to elaborate on the response, if you are just seeing the Volcano for the first time but too frail to work through the whole dungeon, then what I do is check out the entrance (sometimes there are 1-2 of those monsters swimming in the lava), and only defeat those. They drop those fairly often and you don't have to risk dying or engage in much of any combat if you dislike that. It sounds like you plan to go through the whole thing though since you want to unlock the door.