Parachrom is a spring alloy patented and manufactured by Rolex noted for its anti-magnetic properties and durability.
Parachrom is a metal developed by Rolex for use in hairsprings. It is an alloy of niobium and zirconium with an oxide coating. It is said to be completely unaffected by magnetic fields and is able to withstand shocks better than conventional hairsprings. Rolex uses Parachrom in balance springs (Breguet hairspring). The name “Para Chrome” consists of “paramagnetic” and “chrome” (Greek color) together. Rolex invested five years in the research and development that led to this invention, and has applied for two patents based on the magnetic and vibration immunity properties of the spring.
Rolex introduced Parachrom in 2000 in Cal. 4130 used in the Daytona Ref. 116520. In 2005, Rolex modified the surface structure of the material, thickening it and giving it a blue color. The result was Parachrom Blu (often called Parachrom blue), which was used in the updated Daytona as well as Cal. 3186 in the GMT-Master II Ref. 116710. Since then, use of Parachrom Blu has spread to many of the Rolex movement families, including Cal. 3187, Cal. 4160 in the Yacht-Master II, and Cal. 3131 in the Rolex Milgauss adopted Parachrom as well.