The quartz was not useful in the analysis of karat of silver, but those who were well versed in it such as appraiser of silver and money changer determined the karat by eutectic composition that was seen in rust on the surface and crack.
銀品位の分析では試金石は役に立たないが、銀座の銀見役、両替商など熟練者は、表面の錆色、割れ目などに見られる共晶組織から品位を判断したという。