The M620 was a special edition of pens known as the “Cities” series, first released in 2001, all of which are now discontinued.  The purpose of the series was to honor different cities and, towards the end of the run, places from around the world.  There is only one trim variant and size of the M620 since it was released after the 1997 trim change.  These pens are distinguished from the M600 by their color patterns but are otherwise similar.  The M620 pens in general have a crown cap top, double trim rings at the piston knob, a trim ring at the section, and double cap bands.  The furniture is either yellow gold or rhodium plated depending on the aesthetics of the design (as depicted below).  The cap tops will have a painted two chick logo on most of the earlier models before transitioning to the one chick logo after 2003.  There is likely still some carry over of two chick cap tops after 2003 due to the utilization of old stock.  The nibs of these pens are 18C-750 two-toned gold.  Some of the barrels below exhibit translucency.  1.30ml ink capacity.

Berlin

Stockholm

Madrid

San Francisco

Chicago

New York

Athens

Shanghai

Piazza Navona

Place de la Concorde

Piccadilly Circus

Grand Place

NOTE:  The above images have kindly been provided by John Mottishaw of Classic Fountain Pens.