Colourarity is a simple lib that used to registry rarity for Fabric mods. In theory,this mod can run on all of the Minecraft versions with Fabric Loader.
For developers:you can registry your own rarity for your mod by
RarityRegister.registry(Formatting.XXX, YourItemTag);
than, your rarity will be bound on items of YourItemTag,and this item will have a colorful name with your Formatting.