Gold grade is a measure that indicates the purity percentage of gold in an alloy. Because pure gold is so soft, it is
usually bralloyed with other metals such as silver, copper, or palladium to make it stronger. Gold grade indicates
the ratio of gold to other metals in a piece of gold
The most common system for measuring the purity of gold is the karat system (Karat or K). This system consists of 24 parts,
that is, pure gold equals 24 carats (24K).
- The touchstone method: one of the oldest methods for determining the gold grade is the use of a touchstone. In this method,
the gold piece is drawn on a special stone (usually black stone) to leave a trace of gold. Then nitric acid or other acid
with different concentrations is poured on it. According to the amount of color change or dissolution of gold in acid,
the grade of gold is determined
Most of the manufactured gold in the market has an engraved mark or seal that indicates the gold grade. This seal is
usually engraved on parts of gold such as the back of a bracelet or necklace. This mark can be in the form of a number
(such as 750 for 18 carat gold) or in the form of karat (such as 18K).