This US patent, filed in 2002, appears to offer a look backstage of all of it, because it describes a course of much like the one IWC makes use of. Within the patent, inventor Edward Rosenberg signifies that the “course of for forming a metallic article having a black decorative floor” requires an alloy that accommodates “between about 51 and 70 [percent] by weight of titanium, between about 3 and about 17 p.c by weight of niobium, and the stability of a steel chosen from the group consisting of zirconium, tantalum, molybdenum, hafnium zirconium, chromium, and mixtures thereof.” I assume {that a} mixture of those makes up the proprietary alloy that IWC at present makes use of, however nobody can say for sure.
