Coating is very important for neodymium magnet. In regular, people use 3 coating, likes Ni, Zn, Epoxy. Epoxy is most expensive, and then Ni, and Zn is cheapest. But the point is Ni. Lots of customer does not know there 2 type Ni coating. Ni only and NiCuNi. In some cases, magnet should be coated with NiCuNi, but as customer does not that , and just guess they need Ni coating.
So the factory quote it Ni only.
But good supplier will told their customer, you should use NiCuNi their performance is better than Ni only.