Testing for 10K, 12K & 14K
You will need the following tools:
- Black acid testing stone that is washed thoroughly with water prior to each test
- Acids
- Gold testing needles with gold tips - used for comparison with test pieces
Scratch the gold piece to be tested on the stone. Next to this position, scratch the appropriate needle
(10,
12, or 14K). Place a drop of the appropriate acid on the stone where
the gold was rubbed off. If the gold is the same karat or higher, the
colour of the scratch mark for the gold piece will appear the same as
the mark from the needle. If that gold piece is a lower karat, the
scratched deposit will become fainter and eventually disappear.