I'm not an expert in this matter but this "sterling silver" necklace has black spots all over it after 2 weeks of wear. My other sterling silver necklace does not have such issue although I've been wearing it for long time. Don't know exactly what is the reason but googling the question suggested questioning the real quality of sterling silver. anyway, keep in mind that black spots that are also called silver rust appeared just after 2 weeks of use. Also, I ordered 24 inch version but got something like 23 inches, weird. (Seller was Sabrina Silver)