Testing for nickel

Nickel allergy: It's a problem many women run into when they wear jewelry. Nickel is a metal that is commonly used in metal alloys. And not just in cheap materials; even low-content gold is sometimes mixed with nickel. An allergic reaction usually occurs when you have been exposed to nickel for a longer period of time (and if you are sensitive to it, of course). Most coins, for example, contain some nickel, but we never touch them long enough to get a reaction. But if you were to wear an earring with traces of nickel, then that could result in unpleasant reactions. It may cause itching, eczema, or make your earlobes swell up. In short, this is something you really don't want when you're wearing jewelry!

This is why I have always been very cautious about buying metal parts. I have never blindly trusted my suppliers' promises that their products were nickel-free.
Recently, I have started testing my metal products for nickel myself. I bought a nickel-test at an on-line allergy shop. Thy sent me a plain white bottle, containing a substance called Dymethyl Glymoxime. You just need one drop on the metal you are testing, and then you rub it in for about a minute. If your cotton swab turns pink, then your metal contains nickel.
The first time I tried this out, hardly anything happened. The cotton swab turned a bit brownish. Was this nickel, or just some dirt or tarnish on the surface? I looked for some jewelry that I was sure contained nickel.
This is what happened to the bracelet. I put a drop of the tester on the back, and the liquid changed colour immediately. This was pink. This was nickel!

A second bracelet gave even more exciting results. The liquid spontaneously turned fuchsia and spread through the material. Rubbing wasn't necessary, the test was positive.