The watch case is to contain and protect internal component parts, such as movement, dial, watch hands and so on. It also provides the wristwatch with fashional and attractive appearance. In addition to the function the above mentioned, it largely determines the performance index, including water resistance, dustproof property, anti-magnetism, anti-seismic performance and others. According to materials for the watch case, common case models include more than ten different kinds. However, stainless steel is the most widely used.

For Rolex watch fans, they probably know something about 904L steel. So far, only Rolex among watch brands has used fully the material to manufacture watches; while many famous watch brands adopt 316L steel. Obviously the cost of 904L steel is higher than 316L steel, so many people question why 904L steel is so expensive. What are the differences between 316L steel and 904L steel?

The major ingredients of 316L steel include ferrum, chromium, nickel, molybdenum, etc. Generally speaking, the material doesn’t make an impact on human skin. 316L steel with corrosion resistance and good texture is used to produce papermaking equipment, pipelines, buildings, the bracelet and case of the luxury watch, jewelry, medical instruments and so on.

904L stainless steel contains up to 21% chromium alloy, which makes its corrosion resistance comparable to precious metals. It is only applied in some high-tech areas like aerospace, chemistry, petrol chemical industry and surgery. In 1988, Rolex was the first who introduced 904L stainless steel into the watchmaking. So far, Rolex is the only watch brand which has applied widely and systematically the material to produce cases, crowns and bracelets. Its manufacturing process is quite strict. Metals are melted again into the vacuum container after the first casting. With impurities removing and quality confirmation by electron microscope, 904L steel is allowed to make watches. Due to 904L steel with strong corrosion resistance and wear resistance, it must be processed by special tools and high technology.

As for ingredients, 904L steel also contains cuprum in addition to ferrum, chromium, nickel, molybdenum, so it is much more corrosion resistant and more wear resistant than 316L steel. If a watch often touches perspiration or is in humid environments, 316L steel is able to withstand the corrosion. 904L steel is the best choice for those people who are engaged in working at sea or enjoy diving as a sport. As a high-purity metal, 904L steel will become more sleeky and more beautiful after beening grinded and processed. Therefore, the cost of 904L steel is relatively high because of high-difficulty forging. I’m afraid that only Rolex dare to challenge in order to make more practical watches. It is one of reasons why Rolex enjoy the high reputation all over the world. Rolex Split-seconds Chronograph Ref. 4113 is the most expensive watch, which was sold for 1,107,750 Swiss franc at Christie’s auction house.