If you have ever had the opportunity to polish, maybe just even the buckle on a Rolex watch you would start to get an understanding of how incredible the alloy of their steel is. Incredibly tough, resilient, and workable. Other brands in this category pale in comparison. Rolex owns that market for luxury steel and for good reason: price.
The average watch case is made with 316L steel. In fact, you’ll often see this touted on marketing material because it’s known for being 5 times stronger than regular steel. 904L (or UB6) is comprised of a chemical element called chromium, forming a corrosion resistant steel alloy that is not only tough but highly polishable. The alloy is so hardcore that Rolex has a built proprietary equipment used for pressing out cases from solid blocks. For another company to venture into case making and production of 904L, it would literally cost billions to have the correct machines produce the product. So, for now, 904L is a precious metal and “hard” to come by, with only one place to find it.