These come in a nice variety of colored glazes. L is a light blue RFI (radio treatment) unlisted with RFI in the current porcelain guidebook, center is a nice gray and Right is a medium blue color very similar to the JD blue glazes! They all have the number 8834 on the top firing rest and also a capital alphabet letter that varies. I suspect the 8834 is a catalog number but the wide variation of the different capital letters meaning is unknown to me.