Trade measurement laws regulate the buying, selling and valuating of precious stones or metals when using a measuring instrument, such as a scale.
These laws do not cover other factors you consider when determining price, including:
Any scale you use 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 that a scale will calculate weight by, for example a gram, milligram or metric carat increment.
You can’t use a scale to weigh gold, silver or other precious metals when it has:
|Capacity of instrument||Verification scale interval|
|Less than 1 kg||10 mg|
|1 kg or more but less than 10 kg||100 mg|
|10 kg or more||1 g|
If you use a scale below the minimum capacity marked on the data plate it can be inaccurate.
A verification scale interval is denoted as the ‘e’ value marked on the data plate of a scale. Before purchasing a scale, you should check the ‘e’ value to ensure that it meets these requirements.
If you use a scale to weigh precious metals or stones, you must ensure that:
You are responsible for making sure the scale is correct at all times.
We recommend that you check your scales daily to ensure their accuracy. You can purchase a set of test weights from a certifying authority to check that your scales are level, resets to zero and accurate.
We also recommend that you have your scales checked regularly by a technician licensed by NMI (servicing licensee). For a list of servicing licensees, email tmlicensees [at] measurement.gov.au.
NMI employs trade measurement inspectors throughout Australia. They inspect precious metals and stones being sold or valuated to ensure that sellers are following the correct process.
If an inspector finds that you are short-measuring your customers, you could be fined up to $222,000 per offence.
Find out what to do if you get a visit from a trade measurement inspector
To find out more about trade measurement laws or report a suspected breach contact the trade measurement helpline:
Last updated: 8 December 2020
Content ID: 52557