Touchstone 200x100x12mm

Description

Dimensions: 200 x 100 x 12 mm

How to use:

•  Rub the jewelry of unknown karat purity gently back and forth on the testing stone to leave a thin, but clearly visible, metal sample. Use care to take this sample from a place not clearly visible on the jewelry and away from solder joints.
•  With a testing needle, draw a question mark on the touchstone that represents the unknown metal.
•  Start with the 14k testing needle and rub a layer next to the unknown. Label it “14.”
•  Repeat this process, making a layer and then labeling with the 18k, 22k, and 10k testing needles. Now choose the bottle labeled for testing 10k and lightly swipe the applicator across all the samples.
•  After approximately 20 to 40 seconds, place the touchstone in a mixture of baking soda and water to neutralize the acid in one beaker, then rinse in water in the other beaker.
•  Blot the touchstone with paper towels and observe. The 10k sample has dissolved, but the unknown metal is still visible. This confirms the unknown metal is finer than 10k.
•  Next, choose the bottle labeled for testing 14k and swipe it across the samples just below the first test.
•  Allow enough time for the acid to react and neutralize, then rinse and blot the touchstone and observe. The acid has dissolved both the 10k and 14k samples. The unknown metal is therefore 14-karat or slightly higher.