A quick and reliable method to determine the purity of solid precious metals at home is to apply the Archimedes’ Principle using a balance or a scale.
Using the Archimedes’ Principle, first weigh the object normally, i.e. in air, and then weigh the same object immersed in a liquid of a known density and temperature. The apparent differences in mass between these 2 measurements gives the purity or density of the object.
With help of metal density tables available online it is possible to determine the purity of examined object.