I don’t have a great deal of background on this model, for lack of resources, and so I’m going to lift a lot of the following text from its stable-mate, the PKB-2000. It is one of the “long/short” pattern, which Platinum calls a “Pocket-type”, that had a vogue for yet-to-be explained reasons in Japan in the 1960s and ’70s. This model was in a broad mid-range of Platinum’s models; there were many variations on pens costing ¥3000 in the catalogue where I’ve found this model.
In writing, there is a lot of possible variation with these pens, as the points are available in both firm and “soft” grades. Something that Platinum deserves praise for is in resisting the urge to mess around with their cartridge pattern; modern production cartridges will fit these pens, which is not true of similarly-shaped models offered by Pilot. The clip is also laudable, a solid sprung object that should be fairly gentle to the fabric of pockets.
The cap metal on this pen seems somewhat sturdier than the thin aluminum on the PKB-2000– perhaps that’s why it costs 50% more. Surely it’s not just the decorative lozenge inlay behind the point.
Production Run: 1964 – c. 1975; the start is taken from the company’s own history, the end is more in the line of a slightly informed guess.
Cost When New: ¥3000, which in 1964 was about $8.30. This is the same price in a catalogue I’ve seen described as from “the seventies” (but by the contents may be from as early as 1967)– not quite $10.00 in 1975 (for modern value, try this calculator). Given Japan’s long tradition of supporting domestic producers on the backs of export markets, these prices likely don’t represent those to be found by a buyer outside Japan.
Size: 11.9 cm long capped, 14.9 cm posted, 10.2 cm uncapped.
Point: 18K gold.
Filler: Proprietary cartridge, capacity approx. 1.2 ml; the modern converter will not fit.
If you are relying on the preceding information to win a bet or impress a teacher, you should read the site’s scholarly caveat. Remember, this is the internet, and it’s full of bad information.