Do you think we are in use of Touchstone nowadays also ?

Question

The touchstone I'm familiar with is a flat piece of ceramic that has gold in different karats rubbed on them and used to appraise the karats of a gold sample of unknown purity. The most closely matching color indicates the concentration of gold.

Answer 1

Yes, almost every goldsmith or jewellery trader uses touchstone for appraising purity (karats) of gold. This method has been accepted as a recognized method for subjective measurement of gold purity, and has been specified in international standards prepared by ISO.