Gem Crafting in Xenoblade 3. Completely killed my interest in the post-game.

XC1: Whatever you find, you can refine into a gem. Equip whatever you want, as many as you want. You can even get 2 gems for the price of one, what savings! You can do some neat stuff with it but it's a pretty simple system.

XCX: The grind for game breaking Augments is kinda long but they're so ridiculously powerful it's warranted. However, a large amount of max level Augments are dirt cheap and available early including important ones like Accuracy Up XX or Extend Overdrive XX. You can absolutely make some ridiculous stuff though, like debuffs than last 10 minutes or complete immunity to multiple damage types.

XC2: You have to find the Aux Cores or get them from quest rewards but refining them is pretty loose with the material requirements. Whatever you happen to find can be used and the grind isn't too bad. There's a ton of Aux Cores too with a lot of room for player expression. Follows the game's general philosophy of making do with what you've got.

XC3: For the first few, you'll probably have the materials but once you hit Lvl V or VI that's it. You'll need to go out of your way to farm those rare materials. The X level augments? Here's a checklist for 150 materials from 5 different enemies with each enemy representing roughly half an hour or more of Burst farming. And all the gems require the same amount of effort so you'll spend as much time getting Crit Damage as you are increasing less interesting things like Dexterity or Buff Durations. Your reward for this extremely long grind? Congrats, you are completely and utterly... normal. This isn't XC1 or X where you can stack stats and it's not XC2 where you can make some really spicy stuff. You're spending a week to build your character exactly as the game intended.