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Any transaction involving precious stones or metals is deemed to be a trade transaction if the purpose is buying, selling or valuation of items. Even though a number of other factors may be involved in the buying, selling or valuation of a piece of jewellery, such as metal purity, colour, link type, workmanship, rarity or popularity of design, if a measuring instrument is used, its use must comply with trade measurement laws.
Any measuring instrument used to weigh diamonds or other precious stones, must not have a verification scale interval of more than:
The verification scale interval is the graduation size specific to a scale that it will calculate weight by e.g. a gram, milligram or metric carat increment.
A measuring instrument used to weigh gold, silver or other precious metals cannot be used when the measuring instrument has:
Inaccuracies can occur if a measuring instrument is used below the minimum capacity marked on the data plate.
A verification scale interval is denoted as the ‘e’ value marked on the data plate of a measuring instrument. Before purchasing a measuring instrument you should check the ‘e’ value to ensure that it complies with the regulatory requirements.
If a person who is buying, selling or having valued precious stones or metals, is not present during the measurement, they must be provided with a written statement of the weight of the items.
Under trade measurement legislation owners and users of measuring instruments for trade are responsible for:
Where a measuring instrument is used to measure an article over the counter, the measuring instrument must be positioned so that the customer can clearly view the weighing process, the weight and the resulting price per prescribed unit.
If you sell or value precious stones and metals you should conduct regular quality assurance checks with test weights to ensure that the instrument or scale is level, resets to zero and weighs accurately. This should be done at least once a day. It is recommended that you purchase a set of test weights appropriate for your scale from a measuring instrument supplier. Test weights can be expensive but, if well cared for, can last a lifetime.
The main laws covering trade measurement are the National Measurement Act and the National Trade Measurement Regulations. For more information on:
For more information contact 1300 686 664, firstname.lastname@example.org or use our on-line form.
If the buyer is not present
Accuracy of instruments
For more information
What is trade measurement?