Emerald Necklace (Enchantable slot item)

There has been a similar idea that lacked refinement.

Introducing an emerald necklace slot can drastically improve the use of emeralds and enchantments without being game breaking in the slightest, the idea is that you use an emerald, gold and string to craft an emerald necklace, this necklace can be enchanted with any enchantment, but can only have one enchantment at a time. This will allow the player to use a pickaxe without silk touch and still get the results of silk touch, by wearing a necklace with that enchantment applied for example.

A necklace will break at the same rate as the item the enchantment works with, for example, if I have a stone sword and my necklace has looting on it, my necklace will deplete with every swing of the sword, and take on the durability of a stone sword as well.

When depleted, the necklace can be taken to a villager (Cleric possibly) to restore it, at the cost of 1 emerald for tier one enchantments, 2 emeralds for tier 2 etc.