With peridots or rubies plus iron, you can make yourself an infused iron ingot. They can be used to make Infused Diamonds, Infused Iron blocks, and Katanas. If you hit with a katana, you get speed, jump boost, and invisibility.  Infused Diamonds are very difficult to craft. With them, you can make infused diamond blocks. With blocks and normal gem versions of infused diamonds, you can craft Betty, a powerful, indestructible, axe/weapon.  There is also Infused Coal and Emeralds, with their respective block.  Infused gold is one of the more useful infused items.  It is made with some misc metals.  It can be used to make many different items and armors.  It can also make the Infused Clock, which is used for the Time Stone.  And, with some rare items, you can craft an Infused Gold Block.

If you go a step higher, you can make Enchanted Iron, which can make the ultra powerful Notch's Axe.  Enchanted Coal can be used to make the Fallen Sword, an unbreakable weapon that deals 11 damage.  Enchanted Emeralds is one of the most expensive items to craft.  It is part of the recipe for the Sword of Dianite.  Enchanted Gold and Diamonds can be made, but they currently have no use.