PROCESSES OF HALLMARKING

All articles (gold & silver) that are submitted to the Cyprus Assay Office for Hallmarking have to undergo three processes:

	(a)  Sampling
	(b)  Assaying
	(c)  Marking

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(a) Sampling

The number of items taken from a batch and the number of samples taken from these items for testing and analysis shall be sufficient to establish the homogeneity of the batch and ensure that all parts of all articles controlled in the batch are up to the required standard of fineness.

(b) Methods of analysis and other test methods 

The testing of articles of precious metals submitted for marking with the Cyprus Mark consists of the two following steps:

a. the evaluation of the homogeneity of the batch, and

b. the determination of the fineness of the alloy.

1. The homogeneity of the batch may be evaluated by one of the following test methods:

1. touchstone testing;
2. testing by X-ray spectroscopy; and

2. The fineness of the precious metals content is determined by one of the following approved methods of analysis:

 

Gold: Cupellation method.( ISO 11426)

In fire assaying, or cupellation, a small sample of the gold under test is weighed on a special balance.  This is placed with a quantity of lead in a small crucible  - or cupel -  made of bone ash, which is heated in a muffle furnace with a draught of air flowing over the cupel. The lead and any base metals are oxidized and absorbed into the cubel, while the gold and any silver remain as a small button.  The silver is  then dissolved out with nitric acid, leaving a pure gold ‘cornet’, which can be weighed and the gold content calculated by comparing with the original weight of the sample.

Silver: Volumetric (potentiometric) method using sodium chloride. (ISO 13756)

A sample is dissolved in dilute nitric acid. The silver content of the resulting solution  is determined by titration with standard  potassium chloride solution using a potentiometric  indication of the equivalence point.

(c) Marking 

The following minimum marks shall be applied on articles. a) registered manufacture's mark; b) the official mark of the assay office; c) the corresponding fineness mark in arabic numerals;

Marks b) and c) shall be punched on the article by the assay office. Mark a) can be applied by the manufacturer or shall be punched on the article by the assay office.

Whenever possible, all marks shall be placed in immediate proximity to each other.

Other marks, which are not to be confused with the marks mentioned above, are allowed as additional marks.