This is a very complicated problem. Different dynasties and different kinds of gold products have different gold contents.

In the Han Dynasty, the gold content of horseshoe gold and Linzhi gold was about 70%, and the gold cake was over 99%.

The gold content of the red gold bowl in the Tang Dynasty is 90%, while the gold content of the gold and silver alloy is only 30%.

There is also a medicinal gold, which is actually brass, and its gold content may be 0.

That's all I know for reference.