Black PolishingBlack polish Black Polishing is a technique where movement parts are essentially mirror polished to such a high degree that, depending on how the light hits the part, it appears as if it is black. Black polishing is typically only found on high end watch movements as it is a very time consuming process. [Learn More] is a technique where movement parts are essentially mirror polished to such a high degree that, depending on how the light hits the part, it appears as if it is black. Black polishing is typically only found on high end watch movements as it is a very time consuming process.