In jewelry manufacture it is recognized that alloys and other materials should meet the needs of the manufacturing processes and that the resulting jewelry should give good service performance when worn by the customer. To ensure these needs are met, it is necessary to know certain properties such as density, tensile strength, hardness, color, tarnish resistance and precious metal content. It is a balance to ensure that the jewelry meets the needs of being "fit for purpose" while keeping costs to a minimum, for example, by reducing the weight of metal in the piece. Sometimes we measure the properties ourselves but often we rely on data from external sources such as alloy suppliers and the scientific literature. How much reliance can we place on the values we obtain in property testing? Are we measuring the property correctly? Are we measuring the right properties? What can property measurements tell us in terms of their applicability to the manufactuing situation? This paper considers the measurement of the properties of jewelry alloys and of actual finished jewelry. It reviews the important properties, how they are measured and what they tell us in terms of their relevance to jewelry manufacture and service performance. Mechanical, physical and chemical properties are considered. The importance of making measurements in accord with international standards and the need for industry-agreed standards for tesing of actual jewelry are emphasized.

Author: Dr. Christopher W. Corti