When some people rub a gold ring across their face it leaves a black mark but for others it does not. Does this have to do with iron levels?

I teach chemistry and use this as a lesson on The Scientific Method. My students are to develop their own hypothesis as to why they think it happens, then they are to create a data table with as many variables as possible listed: age, gender, skin tone, type of makeup, medications, race, ethnicity, sweat, stress level, eye color, hair color, freckles, acne, etc.

They then test as many people (with their permission of course) during the course of a week. After they have collected their data, the create a report stating their hypothesis, organizing their data, and drawing their own conclusions.

Over my many years of teaching chemistry, I have never found a definitive answer as to why this happens to some people and not to others. I have researched it many times and reviewed the data every year. The only thing we can conclude is that it RARELY occurs in males. Even if you put the makeup a female who gets the black mark wears ON a male who does not get the black mark, he will NOT get the black mark. Crazy.

I just recently found out about this phenomenon. My fiancé rubbed her ring on her cheek creating an instant black line. Her friend also did this; a line appeared but then vanished a minute later. However, my fiancé's line stayed on her face for almost an hour before disappearing. My silver ring also left a mark on her face for an extended period of time. This did not occur on anyone else's face at the table, with either ring, and her finger is not black due to wearing her ring; sometimes her ears turn black due to her earrings. When she was younger, I know she was anemic, and she usually has very low iron. Is there a correlation? I wish I knew. If there really isn't a relationship with the iron levels, it may certainly be the fact that the rings react to specific types of makeup - I have not seen a black mark left on a man's face yet.

I've heard it was stainless steel rings....I've heard it MAY indicate a deficiancy in iron...

when you rub a gold ring on a girls face while she is wearing cover up it leaves a mark take the same girl with a fresh clean face and it does not leave a mark. this would explain why not in males and why not all girls with cover up? different cover ups have different ingredients. the other reason it may not show up on males even when wearing the same make up could be that it is from wearing the make up so often it has become more concentrated in girls and or could be related to hormones also. on a side not I have many silver rings (real silver) and on many painted surfaces is I drag my ring across it it leaves a grayish black mark. maybe the reasons are related.

i think it has to do with makeup and foundation