Not all blue screwsBlued Screws Not all blue screws are equal. Traditionally heat-blued screws, involves... heat! The blue color is achieved by heating the screws to a high temperature in a controlled and clean environment. This process produces a thin layer of oxide on the surface of the screws, which gives them their distinctive blue color. It is not uncommon to find blue screws on a watch movement that were simply chemically treated, and not heat-blued. [Learn More] are equal. Traditionally heat-bluedBlued Screws Not all blue screws are equal. Traditionally heat-blued screws, involves... heat! The blue color is achieved by heating the screws to a high temperature in a controlled and clean environment. This process produces a thin layer of oxide on the surface of the screws, which gives them their distinctive blue color. It is not uncommon to find blue screws on a watch movement that were simply chemically treated, and not heat-blued. [Learn More] screws, involves… heat! The blue color is achieved by heating the screws to a high temperature in a controlled and clean environment. This process produces a thin layer of oxide on the surface of the screws, which gives them their distinctive blue color. It is not uncommon to find blue screws on a watch movement that were simply chemically treated, and not heat-blued.