What does gold filled mean in vintage jewelry?

Gold filled jewelry has a thick layer of gold mechanically bonded to a base metal, making it more durable and valuable than gold plated pieces.

Are the entire earrings gold filled or only the wires?

According to the original card, only the wires of these vintage pierced earrings are gold filled, so the rest of the earring may be made from another material.

What era are these vintage pierced earrings from?

While the exact era is not specified, the original price of $3.00 and style suggest these earrings likely date from the mid-20th century, approximately the 1950s to 1960s.