The industry standard stainless steel is 316L. In addition to watches, this alloy is also commonly used in the food industry, the medical field, and a wide variety of water and marine applications. You may see some watch brands refer to 316L as surgical grade steel or marine grade steel. Its popularity in these areas comes from the properties which make it resistant to rust and corrosion. 904L steel takes the resistance to corrosion up a notch.
Rolex 904L Steel:
In the watch community, 904L is largely regarded as being a Rolex thing. Even the Wikipedia entry for 904L stainless steel has been edited to include a Rolex mention (well done, Rolex!):
"In 1985 Rolex became the first wristwatch manufacturer to utilize 904L grade steel in its watches. Rolex chose to use this variety of steel because it takes a higher polish than other grades of steel and provides greater corrosion resistance, though it does not machine as well and requires specialized equipment to be properly modified into the required shapes."
Perhaps Rolex deserves credit for being recognized as the first brand to sell watches with cases made out of 904L steel, but this has led many to think that 904L was a Rolex invention or a material exclusive to Rolex.
It could also be due to the verbiage around the term Oystersteel, which Rolex defines as:
"…a steel alloy specific to the brand. Oystersteel belongs to the 904L steel family, which is particularly resistant to corrosion and acquires an exceptional sheen when polished." –source
Notice how it says it is an alloy specific to Rolex? Rolex has another blurb on their brand history page that claims they use their own alloy of 904L steel:
"Rolex's steel watches are manufactured from Rolex's own 904L alloy, known as "Oystersteel" from 2018."
This is interesting because one would assume an alloy is determined by the properties that compose it. In other words, if it is "Rolex's own 904L alloy" then wouldn't changing the composition mean that it is no longer pure 904L steel?
Is 904L steel a precious metal?
To say Rolex is serious about their 904L steel is an understatement. Their advertisements have gone as far as calling it a precious metal (gold and platinum are precious metals).
Rolex Precious Metal 904l Magazine Ad
Like the vintage Rolex ad above, several areas of their current website (as of 4/2021) also compares 904L steel to precious metals…
"Most commonly used in high-technology and in the aerospace and chemical industries, 904L steels are comparable to precious metals for their anti-corrosion properties and acquire an exceptional sheen once polished." –source
And again here:
"904L steels are commonly used in high-technology and in the aerospace and chemical industries. Their excellent anti-corrosion properties are comparable to those of precious metals. Rolex masters in-house the entire manufacturing process for its 904L steel watch components." –source
Ah, so that explains how a stainless steel watch can cost over $10,000…
Rolex and their use of 904L steel has largely gone unchallenged in the watch industry for decades. Now, as brands scramble find any competitive edge in a saturated market, we're seeing other watch companies start to jump on the 904L train. But is 904L really that much better?
