Used to determine karat content of gold. Needles and item to be tested are rubbed on test stone and treated with acid to determine match.
#56.705 - Set of nine needles for 4, 6, 8, 10, 12, 14, 16, 18 and 20 karat gold
#56.706 - Set of four needles for 10, 14 and 18 karat gold plus silver
#56.707 - Set of five needles for 8, 10, 12, 14 and 18 karat gold
(Shown picture for reference. Each items sell seperately)