Review (4/5): Works with a little elbow grease, FAINT results
You really have to work at this to make sure you get a result, and you must be careful that you got equal amounts of each solution on the cotton swab. I accidentally got too much of Solution B, and got a negative result on something I knew had nickel. Also, you have to really rub hard for 15+ seconds, and then you see a FAINT, faint pink on the cotton swab. It's very subtle.
It would have been helpful if the makers included something to use as a "positive control", something that contained nickel so you could see what a positive test looks like and know what you're looking for while testing unknown items. I highly suggest that users find their own positive control - find something you know has nickel, and test that to see the pink and know you're doing it right.
Also, this seems to release ammonia gas when the solutions are mixed, so use in a well-ventilated area, and don't put your face right over the swab or item being tested or you'll get a whiff of ammonia in your nose/eyes.
As it turns out, real surgical grade stainless steel does test NEGATIVE for nickel! (And I tried really, really hard to get a result on that one!) I was using this test kit to double-check my earring-making components to make sure there was no nickel content for making hypoallergenic earrings. Again, I HIGHLY recommend using a positive control (and perhaps a negative non-nickel control as well) to make sure your results are real and valid.