Gray is one of the older Mosser Collie colors and very hard to find. This one was sold in April, 2017. As far as or research can tell, the last one that had shown up on eBay (correctly listed) was sold in 2008!
Gray may not sound very exciting, but it is really quite beautiful! The glass is opaque, the color is a soft, light blue-gray with some darker areas. This collie has a large M on the base, marking it as pre-1981.
The Mosser Sitting Cat in gray is also unusual but does show up occasionally.