Ring de-plated in aqua regia. Timelapse footage of a metal-plated ring being de-plated in aqua regia, a mixture of concentrated acids. Concentrated hydrochloric acid (HCl) is added first, followed by a smaller amount of concentrated nitric acid (HNO3). The mixture produces yellow fumes and bubbles as the acids react to form nitrosyl chloride (NOCl) and chlorine gas (Cl2). This mixture of acids can dissolve gold and platinum. The blackened ring at the end of the clip indicates that the gold or platinum plating has been removed by the aqua regia.