1. Selection of Polishing Machines and Compounds
The polishing machine offers speeds ranging from 1400 to 2800 RPM. When using zinc silver alloy polishing disks, it is recommended to choose a 150mm disk at 2800 RPM to achieve the Bayer layer recrystallization temperature. Hardwood disks are also an option. The polishing powder selection is:
2. Polishing Specific Methods
Properly preparing the polishing disc is a crucial step. The method involves mixing commercially available diamond polishing compound or homemade diamond micropowder with cream to form a paste. Then, apply a thin layer of this paste around the polishing disc at a distance of two-thirds the radius from the center. Use a large piece of crystal or another hard material to press the diamond polishing compound into the disc, creating a polishing agent that combines the disc's components with the diamond polishing compound. Push this polishing agent towards the center of the disc to evenly cover it with a layer. This polishing agent layer is characterized by its dry, non-sticky texture. Gemstone sanding and polishing can be done simultaneously at one location. Simply place the facet flat on the polishing disc, apply appropriate pressure, control the polishing time, and achieve satisfactory results. For larger facets, polish around the outer edge of the disc. For smaller facets, choose a spot closer to the axis.
3. Advantages and Disadvantages of Diamond Micro Powder Polishing ① Due to the significantly higher abrasive capacity of diamond micro powder compared to other polishing powders, it can rapidly refine and flatten facets, resulting in a superior mirror-like finish and enhanced crystal luster, fully showcasing the gem's brilliance. Furthermore, dry polishing using diamond micro powder raises the recrystallization temperature of the facet's Byer layer faster than water-based polishing. Additionally, the elasticity of zinc-tin polishing disks is much lower than that of organic glass or foam disks, making diamond micro powder polishing both faster and of higher quality than other polishing materials. ② When using oil-based or paste-like diamond polishing agents, only a small amount of waste is scraped off the gem's edge, and it can be recycled. In contrast, water-based polishing agents, with continuous addition and the disk's constant rotation, cause a large amount of polishing agent to spray into the air or onto other items, polluting the environment. Chromium and zinc polishing materials are particularly harmful to humans. Therefore, diamond micro powder polishing is undoubtedly cleaner and does not cause environmental pollution. ③ Although diamond micro powder is more expensive than chromic oxide or decorative oxide, once the polishing agent layer on the zinc aluminum alloy disk is properly mixed, the subsequent addition of polishing powder is minimal, only requiring the maintenance of the polishing agent layer. Moreover, the fast and efficient diamond micro powder polishing reduces labor costs, offsetting the higher cost of polishing materials.