The 222 is made of celluloid, and this particular one has the "platinum lined" (PL) design which I find mesmerizing! According to a catalogue from c. 1932 the 222 was available in black, red, blue, and green. But, the catalogue also has a disclaimer to the effect of "the coloured pens are subject to fashion, so changes to the colour range are reserved". Maybe the PL variant came into fashion a little later?
The catalogue also indicates that the 222 replaced the previously available No. 15 size pen. Both are relatively small.
The "papyrus" clip on this pen is quite elegant, in my opinion, and it is period correct for the 1930s.
The 222 in PL is a rather rare pen. Collectible Stars I rates it a 10 on a scale of 12, which the book explains is a "once in a blue moon" find with around 25 pieces estimated to be floating in the market. While I don't know how accurate this is, I must agree that I have never stumbled upon a 222 PL before. I have seen 122 PL pens come up for sale, and while these are more expensive than the 222, Collectible Stars actually rates them lower in rareness at a 9 out of 12.
Interestingly, my 222 is a button filler - a rather simple and efficient mechanism. You can read more about it here --> Danish No. 1 bandless. But, the 22x series was advertised - and is typically found - as a push knob filler or Stoßfüller. You can read more about the push knob filler here -->422. The only exception was the 221 "kurzes Damenformat" or "short, lady format" which was a Druckfüller or push button filler like mine. See the clipping from a c. 1932 catalogue. Could it be possible that some 222s were fitted with push buttons too? A knowledgable dealer I know says he has personally examined about seven 222s in different colours all with push buttons. So, who knows!
For bibliography, see Resources page -->link