Stainless Steel Grades
Stainless steel used in watches are divided by different grades, and each grade has its own composition of metals – giving it unique strengths and weaknesses. Following, we will describe the pros and cons of each grade.
Fake Stainless Steel
The cheapest watches (e.g., replicas and knockoffs under $100) typically use alloys that aren’t stainless steel by definition, even though they often are sold as “stainless steel watches”. The problems with these cheaper alloys are that they easily corrode when exposed to other elements, that they easily lose their color, and that there are no processes ensuring the composition and safety of the materials used.
Stainless Steel
Stainless steel is an alloy (i.e., a mixture of metals) made up of primarily iron, carbon and at least 10.5% chromium. This composition ensures resistance against tough conditions. Unlike other metals, stainless steel doesn’t stain, rust or corrode in contact with water. This makes it a suitable and popular material for watches. Stainless steel used in watches are divided by different grades, and each grade has its own composition of metals. The most common are: 304L. The most common quality grade of stainless steel is 304L. This grade contains between 18 and 20 percent chromium and up to 12 percent nickel. Stainless steel watches with the 304L grade have a high resistance to rust, and withstands corrosion from most oxidizing acids. However, the weakness of 304L is that it is susceptible to corrosion from chloride solutions that might cause “pitting” (i.e., small holes in the metal).
 
314L Stainless Steel
The most common quality grade of stainless steel is 304L. This grade contains between 18 and 20 percent chromium and up to 12 percent nickel. Stainless steel watches with the 304L grade have a high resistance to rust, and withstands corrosion from most oxidizing acids. However, the weakness of 304L is that it is susceptible to corrosion from chloride solutions that might cause “pitting” (i.e., small holes in the metal).
316L Stainless Steel
316L is the stainless steel grade chosen by vast majority of watches. (e.g Omega watches) Stainless steel watches with 316L are quite similar to 304L, with the difference that they incorporate 2-3 percent molybdenum – an element that increases the corrosion resistance against chlorides.
904L Stainless Steel
This is the stainless steel famously used by Rolex. It has superior resistance to corrosion due to its high amounts of chromium (19-23%), molybdenum (5%) and nickel (23-28%). It is also extremely expensive.