What’s the difference between Silver, and Oxidized silver?

I saw these Pandora earrings that I was thinking if getting for my mom. She has very sensitive ears, and can only have sterling silver, or real gold. The website said that its made out of Oxidized silver. Can she still wear these? And what’s the difference?

Oxidised silver is darker and its finish is less sparkling.

	Pandora STELLA Oxidized Silver Gold Diamond Star Pendant + Trace Chain LOT SET $154.95