Even though "Platinum Blue" is the name by which RR china collectors commonly refer to the gray/blue New Haven china, it is really a poor choice of names. As per the manufacturers, that name is intended to denote the base color of the china. Indeed, much "Platinum Blue" china has no decoration other than the base color - specifically, no deco figures. While it is commonly said that "Platinum Blue" china that is not RR marked (even that with the deco figures), was not used by the New Haven, it is even less likely that "Platinum Blue" china without the figures was railroad china. Being back stamped with the words "Platinum Blue" is certainly no guarantee of RR use! That said though, the last known replacement for Platinum Blue china on the New Haven was "Caribe", which was essentially the same china, but with no deco figures, and no RR markings, so I suppose that the possiblility of RR use of undecorated, unmarked Platinum Blue china does exist. Even so, whether used or not, like Caribe, collectors of RR china assign non-RR-marked Platinum Blue china of any sort liitle or no value.