Study on Gold Content in White Karat Gold Alloy Jewelry by Cupellation Method

The gold content in white karat gold alloy samples is determined by the cupellation method,and the effect on the testing results of gold content with the test portion weight of the proof gold and samples,the variety of cupels,the additive amount of copper and silver is studied.At the same time,the accuracy of the results determined by cupellation method is also validated by using ICP.The results show that when the test portion weight of the proof gold and samples is reduced to 160.00~200.00mg,there has no influence on the result of gold content.Respectively using magnesium oxide and bone ash cupels,the result deviation of gold content in the samples is within the allowable deviation of the national standards.The result of gold content in samples is much more closed to the theoretical value by adding proper copper in the proof gold.The additive amount of silver(2.5 to 2.7 times equal to the weight of the proof gold) in the proof gold and samples has no influence on the result of gold content.In the AEAO Round Robin 2006,National Jewelry Quality Supervision and Inspection Center(NJQSIC) in China acquired much well testing result by using the cupellation method in this paper.