ADK is the symbol of the manufacturer, and G750 stands for gold with a gold content of 75%, also called 18K gold. Some 18K gold jewelry will be called G750 or AU750 instead of 18K, which means the same as 18K, because G is the initials of Golden English. AU is the chemical symbol of gold. This is two concepts with PT950, and PT is platinum. PT950 indicates that the platinum content is 95%. G750 indicates that the gold content is 75%. Nowadays, lettering printing of jewelry is generally like this. The factory standard is ahead. The color is in the latter position. The weight of diamonds or other precious stones will be marked at intervals.