Well, we learn new things from the discussion on Sinn watches.
Does Damasko watches also the same as Sinn in terms of being scratch-proof on the "Black-coating"?
Here is what Damasko said
"The Watch Case
.....we took out patents for 20 closely related martensitic sorts of stainless steel which highly exceeded our expectations. They are absolutely nickel-free, offer a good corrosion resistance, and can be tempered up to 64 HRC/800Vickers which is four times the hardness of every other steel currently used in the watch industry.
What makes this material so special is the fact that the molten steel is enriched with 0.35% nitrogen under high pressure. Nitrogen and carbon are responsible for the hardness of the alloy. Under normal circumstances it takes about 1% of carbon to temper a martensitic steel up to 60 Rockwell but the low nitrogen content of our steel only requires 0.35% of carbon to achieve this superior hardness and in addition to that leads to an excellent corrosion resistance which is many times higher compared to other temperable martensitic steels. Due to the special process of hardening we call this steel “ice-hardened, nickel-free stainless steel”. This material is patented for our applications and Damasko makes exclusive use of this pioneering material.
The entire watch case, including hardened crown and pushers is designed, engineered, and machined at our factory near Regensburg. Until the end of 2002 we supplied our cases to a well known German watch brand but from now on these cases will only be available through Damasko.
After the special heat treatment mentioned above our steel reaches a maximum hardness of 62 Rockwell which makes it superbly scratch-resistant. You have to search hard to find a common household item ( apart from a sapphire nail-file or a brick) that is able to scratch the case.
Due to its superior performances this steel was mainly created for aeronautical use in:
- ball bearings for jet-engines
- rotor bearings for helicopters
- fuel pumps of the “Space Shuttle”
- high-speed bearings in CNC lathes
- dental and surgical instruments
"Here is mine