the shafts marked Schon 13 on the joint collar were made for one year only, 1993. In 1994 they started marking the shaft vertically above the joint collar. the 13 probably references 13mm .
Schon marked their shafts joint collars from 1987 till 1994
I've read here and in the Blue Book that Schon only marked their name on the joint collar for only one year i.e. 1993.
However for the past several years I've been looking at the early Schon's I must have seen over 200 for sale where the joint collar is marked "Schon" or Schon 13 or Schon 12.75 and even Schon 12.50. Those plus the Schons not put up for sale must surely be more than their output for one year.
I recently enquired about a cue listed as a 1990 that had joint collar markings. I queried that date and the seller told me that he'd researched this and John Fuhrman at Schon had told him Schon put their name on the collar from 1987 till 1994.
This seems to make sense, a call to Schon can call confirm this.