Testing for gold with acid focuses on the fact that gold is a noble metal which is resistant to change by corrosion, oxidation or acid. The acid test for gold is to rub the gold-colored item on black stone, which will leave an easily visible mark. The mark is tested by applying aqua fortis (nitric acid), which dissolves the mark of any item that is not gold. If the mark remains, it is tested by applying aqua regia (nitric acid and hydrochloric acid). If the mark is removed, then this test dissolved the gold, proving the item to be genuine gold. More accurate testing of the item for its fineness or purity can be done through the use of differencing strengths of aqua regia and comparative testing of gold items of known fineness.
Specific Gravity Test
We offer Specific Gravity testing for gold to our clients.
It works by measuring the gold’s mass in air & water to give almost the exactly the same value. If you measure the water displaced, you can determine the volume and compute the density. The density of pure gold is 19.3 g/mL. Knowing your density and this value you will be able to compute the purity.
Gold for export is tendered for assaying or valuation in the presence of the exporter, the Mines Monitoring Officer and the National Revenue Authority (Customs Officer).
Gold is analysed to certify purity% in the presence of the Senior Mines Monitors, the Exporter and Customs Officer, National Revenue Authority
After the analysis, gold is then re-weighed to cross check.
Specific gravity-(SG) method is used.