Types of Gold Assays

Awni K. Kaloti is the owner and director of AgAu Solutions, a precious metals assaying and trading company in Miami. An accomplished entrepreneur, Awni K. Kaloti has also been at the helm of Kaloti Group International since 1984. AgAu specializes in gold, silver, and platinum, but works with all precious metals.

Detecting the quality and purity of gold is critical to the precious metal trade. To that end, there are several techniques to assess metal objects. Stone assaying is the most direct and common technique used in the course of normal business. Stone assaying involves dragging the metal across a finely grained stone. The streak of metal residue left on the stone can be used to estimate gold purity and gold content of the piece.

X-ray fluorescence is more complex and involves bombarding the metal with x-rays. The composition of the metal is determined by measuring the energy levels of the light emitted (fluorescence) from the metal as a result of x-ray exposure.

Last, a fire assay is used on large amounts of gold and involves melting the gold along with lead oxide. After it’s melted, the lead/gold amalgam is placed in a special container that absorbs the lead and leaves behind only gold. The quantity of the remaining gold is measured against the remaining sample to determine purity.