"Gold will turn white, which may be caused by the friction between gold and white hard metal, or it may be caused by the unintentional pollution of the gold surface by mercury metal substances or daily necessities containing mercury metal. If the surface of gold is white, it is suggested to send the gold to the gold shop for flame gun treatment to restore the gold to its original state. The reason why gold is white may also be that the surface of gold is accidentally contaminated with mercury, or that gold is accidentally contaminated with daily necessities containing mercury, resulting in white spots on the surface of gold. If the surface of gold turns white, it is suggested to send the gold to the gold shop for treatment, and let the gold shop master spray the gold with a musket. Mercury has a very low melting point and will evaporate immediately after heating, which will restore gold to its original appearance.