Find... Twilight crystal
Find it Another crystal you can only find towards the end of the game in Th🐓e World That Never Was. Assassin Nobodies drop them and they're used to make the powerful Ultima Weapon.

Find... Blazing gem
Find it Fat Bandit and Fiery Globe Heartless drop these in Aladdin's Agrabဣah 💟level. They're not particularly strong, but can be used to synthesize a helpful Slayer Earring accessory.

Find... Bright gem
Find it There are loads of places to find these in💮cluding Space Paranoids and Pride Lands. Aerial Knockers, Magnum Loaders, Surveillance Robots and the Bulky Vendor all drop them.

Find... Dark gem
Find it To find these, visit the Bea🥃st's Castle and defeat either a Gargoyle Knight or a Gargoyle Warrior. You can use it with free development to create a really rather useful Expert's Ring