These were done using the black-coloured steel nibs to suit the HongDian model 1850 Black Forest. I can't tell you whether the performance and differences mirror that in the silver- and blue-coloured nibs for that model.
By the way, two things I've since learnt from first-hand experience:
the cap on the HongDian model 1850 is not very good at preventing ink evaporation; this holds true for both the Black Forest and Birch Forest variants; and
Lamy T53 Obsidian ink is very nasty stuff once dried out in a pen!
Originally posted here: