HOW TO TEST SILVER
Scratch the metal in question onto the testing stone; be sure the testing stone is clean and free of any other materials. Then, scratch the 999S needle next to the original sample. Once you have visible lines to work with, place a small drop of the silver testing solution and look for one of the following results:
Dark Red = 90-100% Purity
Light Red or Brown = 80-90% Purity
Light Green = 65-75% Purity
Creamy White results can indicate that the item is sterling silver
Green results can indicate that the item is silver plated.