I love that fired effect, especially the fact that it's done on the nib, too. The pen is gorgeous!
In answer to the person who had their fired finish flake off the pen: I have a Kaweco Fireblue Liliput that has this type of fired finish. It's stainless steel that has been fired. I've had it now for a couple of years and I use it pretty often, and I've never had any problems with the finish. I'm no expert, but I think it has to do with the quality of the basic material and the technique used in the firing. It seems like my Fireblue Liliput is fired "deeply," and that it's not just a superficial coating. Perhaps the Nemosine pens don't start with real stainless steel or titanium; they might just start with a cheaper base metal and then add fire. All this is just speculation on my part.
I seriously doubt whether you would have that problem with the pen pictured here!
Is the nib fired or just the pen? The reason I ask is because that fired finish is an oxidation layer applied using heat. The thickness of said coating determines the color. Of course different metals have different properties and the matte finish of that nib would tend to "hold" the oxidative layer I would think.
However, the coating did not "flake off". The ink ATE IT OFF. The ink, assumedly, is acidic, and acid is what is used to remove oxide layers. As such, there was no stopping it. Acid + oxide layer = no oxide layer.
It's probably possible to coat the nib with something which will prevent this, at least for a decent amount of time. I don't know what that coating would be, as I haven't researched this, however I'm sure that it is possible. I would hope that with such an expensive pen this would have been done.