What does 14K mean stamped on the inside of a ring?

Answer 1

A karat signifies how pure gold is and the higher the more gold there is. Pure gold, which is 100%, is too soft to use so it often has other metals mixed in to make more durable. 14 karat gold is about 58.5% pure gold.

Answer 2

It means the gold the ring is either composed of or electroplated with is 14 karat, which is standard for jewelry.

I disagree. Normally 14k will signify that the ring is 58.5% pure gold (14 karat), not plated. The only time it should signify plating is if there are letters after the 14k such as GP (gold plated), GF (gold filled), etc. Do keep in mind though that jewelry is not always properly marked and the piece should be checked by a professional or other home test means.