Not so much the diamonds that does it for me, but other things seem to say Runde. The dashes are a bit thick, typical for Runde. The butt sleeve pattern became sort of a standard for a Schon cue later as well. The butt plate, in addition to being a bit shorter than the usual 1.5 inches also has a bit of a squared off end, similar to other Runde cues. Also, those ferrules either look like Micarta, or whatever material became the Schon standard with and after Runde. Could also be a custom Schon in the earlier days, but I doubt it, given the wrap. They didn't too many with green speck linen.
All the best,
WW