Glass tables can be easily found in many dining areas. But people always complain that they are easily scratchable. Here my friend has tried to use normal plastic (which has very low hardness) to scratch the glass top, what I can observe is it actually give small damages to the surface... If according to Mohs Hardness Scale (Or some other theoretical tables), glass has higher hardness than normal plastics. But what are the reason behind this? I'm not an expert nor student in material science. Any explanation will be greatly appreciated. Thank you very much!