Assaying

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toetssteenAssaying with the touchstone
The touchstone testing method is a fast non-destructive screening and assaying method. The kind of precious metal and the fineness are determined by testing the colour and chemical resistance. The materials used are touchstones, touch acids and touch needles (alloys with an accurately established fineness of precious metal).

The advantage of the touchstone testing method is that in principle every part of the article can be tested.

cupovenLaboratory assaying
In the laboratory the touchstone method for platinum, gold and silver articles will be supported by the following methods:

  • potentiometric titration for silver;
  • (micro) cupellation for gold;
  • X-Ray Fluorescence Spectrometry (XRF) for compositions of precious metal alloys.

Legal standards
The legal standard of fineness in the Netherlands are for gold 585, 750, 833 and 916 parts per thousand, for silver 800, 835 and 925 parts of thousand and for platinum 950 parts per thousand. Articles can also be hallmarked at the finenesses recognised by the Convention of Vienna. Please bear in mind that not all finenesses recognised by the Vienna Convention are accepted in the Netherlands.

nl-assayMeasurement of layer thickness of gold or silver
WaarborgHolland is able to determine if articles with a surface of precious metal on non-precious metal comply with the relevant requirements of standards or specifications. If articles fulfil these requirements, they can be applied with the guarantee mark Q-tested.