Raimey,
I'm not sure what the Schilling forge mark looks like so I cannot say. This is normal, standard, plain, small s, not "sharp" or fancy.
The encircled rhombus (diamond) is on each tube, near the small s. The four points of the rhombus are touching the circle, and the four sides of the rhombus are slightly concave.
With kind regards,
Jani