Hi,
In my 1970 copy of 'A dictionary of Marks' edited by Margaret Macdonald-Taylor , page 188, I found this reference that concurs with one of Tigerchips suggestions :
"Berlin,Wegely's Porcelain Factory,
Hard paste Porcelain made 1752-57
in blue,or impressed sometimes with numerals arranged one above the other in two or three tiers. These perhaps indicate mould numbers"
I have added a photo of the page, I'm unsure if this is appropriate, not sure if its out of copyright after 38 years!!!
Warmest Wishes
John