What does roc 10k mean on a brooch?

"ROC 10K" on a brooch indicates that the piece is made of 10-karat gold, which contains 41.7% gold and 58.3% other metals. The "ROC" may refer to the manufacturer's or designer's mark, a specific brand, or a hallmark related to the brooch's origin. This designation assures buyers of the quality and gold content of the jewelry.