Waterman introduced- iirc- the cone cap fountain pen (a straight appearing pen, but tapered inside the cap for smooth fit onto a tapered section) in the mid 1890's. This eyedropper-filling style still was in production after 1917, possibly (catalogues at home) into the mid 1920's.
The #12 was amongst the first released and early on was available in black and in red/black mottled.
Today's example is a later #12 (indicating #2 nib size and having someimplication for overall pen size), as it has a clip, lacks imprint on cap, has somewhat late style barrel imprint etc.
It packs, not uncommon to these, a very flexible nib.
But, what caught my eye was the condition of the pen and the intensity of color.
Most mottled pens I see tend to have very subdued red portions. Perhaps this is due to the original look found on earlier versions ofthe pen that I usually see. Perhaps due to "typical" fading. Many pens have weak imprints today, again, probably due to use/wear or due to verly aggressive polishing by collectors, in which, too, too much heatwas generated.
This one... pops. Not only is the imprint very sharp, but the red is about the most bright I've seen on one of these. AND, there is more red (vs black) than I see on most of these.
A lovely pen.
regards
David