What type of earrings are these vintage rhinestone earrings?

These are pierced earrings featuring rhinestones in green and amber colors, designed as vintage costume jewelry.

What does it mean that the earrings need backs?

The earrings currently do not have their original backs, which secure them to pierced ears. You will need to provide replacement earring backs to wear them.

What is costume jewelry?

Costume jewelry refers to decorative pieces made from inexpensive materials such as glass, rhinestones, and base metals, designed to imitate fine jewelry.