Why does jewellery sometimes leave black smudge marks on skin or clothing?
Cosmetics and metal abrasion
Cosmetics are the most common cause of jewellery blackening skin or clothes. Cosmetics often contain compounds like zinc oxide, titanium dioxide, ferric oxide, and calamine. These are often abrasive and wear or rub off very tiny particles of metal appearing as jet black dust. When this dust falls on absorbent surfaces, like skin or clothing, it sticks creating a black smudge.
The effect and result is similar to using a Sunshine Yellow Polishing Cloth. These cloths are impregnated with micro polishing compounds and when rubbed on precious metals a black residue is left on the polishing cloth. The same process is happening on your skin when the metal in your jewellery comes in to contact with the cosmetics.
Most sun block creams contain micro or nano zinc oxide particles, so you can expect the same smudging as found with cosmetics. In this case forego wearing the jewellery NOT the sun block.
Prevention may not be possible, unless you forego wearing cosmetics. You can try the following.
- Remove jewellery when applying cosmetics.
- Avoid wearing jewellery on areas of skin where cosmetics have been applied.
- Thoroughly wash and dry jewellery after wearing.