For this test you need a touchstone, testneedles and test acids (mixture of acids and/or salts). A testneedle is a brass needle to which a gold alloy has been soldered, of which quality has been determined closely.
To make a touchstonetest of a gold or silver object, we need:
- An object to test
- Acids for 8, 14, 18 and 21.6 karat gold. There is also acid for silver.
- A touchstone
- A testneedle
We use a needle of 14 karat because we expect that the object is also 14 karat.
The test goes as follows:
Scratch with the object on the touchstone so that there a considerable gold line lags behind. By putting a gold line with a testneedle beside this line you can stipulate, after the influence of a couple of drops acid on the touchstone, the quality. The testmethod is a method of research where especially experience and insight of the assayer is important. The method in itself is simple to learn but nevertheless it will take years to become a good assayer.
Caution!
When white gold is to be determined by using acid for gold, gives stainless steel the same result. Stainless steel does not give an reaction when acid 8, 14.18 and 21.6 kt is used and is for the inexperienced assessor difficult to assess. When using acid for Stainless steel is it very easy to determine whether it is Gold or Stainless steel.
1.
Use a clean touchstone, if it is not clean it first with the cleaning set. Then scratch a thick line with the jewelry piece on the touchstone.
2.
Scratch another line next to the line with the 14 karat testneedle. Make sure that the lines are full. It works best on a touchstone of good quality.
Scratch another line next to the line with the 14 karat testneedle. Make sure that the lines are full. It works best on a touchstone of good quality.
3.
Drop on the two lines 14 karat acid. Wait a view seconds to let the acid take affect, then wipe it off with a cloth.
Drop on the two lines 14 karat acid. Wait a view seconds to let the acid take affect, then wipe it off with a cloth.
4.
Are the lines still visible and the color the same, you can be sure that it is 14 karat gold.
