14k Gold

58.5% gold, 41.5% copper

It can be cleaned with any jewelers cleaner, cloth or baking soda.

 

14k gold filled

This is a gold overlay, made by heat and pressure-bonding a thin layer of gold to a brass core. The value of gold-filled is greater than gold-plated because gold-filled has an actual layer, not just a microscopic film of karat gold. In applications where gold wire is necessary I use 14k gold filled because it is stronger than 14k gold.