Can anyone tell me if the Waterman Graduate takes (short) international cartridges like the Kultur? (or is it constructed in a way that it only takes (long) Waterman cartridges like the Phileas or Ici et La?)

As far as I can tell, the Kultur/Phileas are basically the same pen, and take both standard & short cartridges. The Ici et La only takes the short (mini) cartridges. Generally, any pen that uses a long cartridge will take a short one, you'll just run out of ink faster.

The Graduate takes both. Also it will hold 2 short cartridges, if you put the 'spare' one in upside-down.

The WATERMAN GRADUATE takes short and long cartridges or filler, the actual ICI ET LA takes short and long cartridges, only the first edition takes only mini ink cartridges, J.M.L.

Ok, the Graduate and the Ici et La take both short cartridges. Thank you for your replies.