In April 2018 Ebay seller coolcc515 from Rochester, Michigan in the USA was selling a lot of genuine Chinese plates. However, tucked in amongst all of them are 3 mint plates not for use on public roads.
Sometimes called factory plates or inner factory plates, they are used in pedestrian precincts, parks, factory grounds and other places that are not public roads. There are several pictures of these plates on vehicles on the www and that have been taken by plate people and all show that the genuine ones are officially issued. Nearly all of them are pale green with the first three characters yellow, white, yellow with the rest after the dash white. Most have the multiple embossed logos that officially issued plates have, the screws with seals on them and low numbers although there is obviously some blocking by place or maybe vehicle type. Vehicles range from police golf buggies, pedestrian area sweepers, Jeep type vehicles, just all types basically that are not used on public roads..
This picture is of 37 mint interior (my name for them) plates with all sorts of numbers, colours, font sizes, etc. If you look carefully you will even find the same registration from the same place in different colours. They have been sold by several Chinese sellers but a lot of them have originated with coolcc515.
All these plates are without doubt made in back street plate shops and are not official, legal or (in most cases) even correct.