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Gold Purity Testing

2020-5-18Table of ContentsDescription of Touch Stone and Test NeedlesMethod of UsingAccuracy Possible Description of Touch Stone and Test Needles The touch or test stone is practically a small black whetstone. Test needles Fig. 47 are a number of slim pointed brass fingers one end having gold points of different fineness expressed in karats the karat is the jewelers standard of measure for gold

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