Why there is a loss of weight in gold after polishing it?

The loss of weight in gold after polishing occurs primarily due to the removal of surface material. Polishing involves abrasion that can wear away a thin layer of gold, particularly if the polishing compounds or tools are too aggressive. Additionally, any contaminants or impurities on the surface are also removed during the polishing process, contributing to the overall weight loss. This loss is usually minimal but can be significant depending on the extent of the polishing.