The M620 Berlin is high in my rankings as my favourite pen in my collection. The marble effect that occurs in four of the city series pens is most striking in green.
This is a pretty boring broad nib, with a large round tip that does nothing for me.
Keshimurasaki means offset purple, this very muted greyish, purple shade was used for formal kimono dresses during the Heian-era (700~1100 CE). It is a very subtle colour that is not shown at its best in these scans.