The most common European gold marks are 1000 for 24 karats, 958 for 23 karats, 750 for 18 karats, 585 for 14 karats, 416 for 10 karats, and 375 for 9 karats, and they all indicate the purity of gold. Other markings include a lion's head which meant the item was tested and marked by the London Assay Office, an anchor for the Birmingham office, a castle for Edinburgh, and a rose for Sheffield.
The International Convention on Hallmarks members have their own assay office marks like letter P for the Czech Republic, letter H for Hungary, three crowns for Sweden, and a horse with the letters NL for Holland. 14K R.G.P. stands for rolled gold plating where a base metal has a gold layer applied on it. 14K H.G.E. stands for hard gold electroplated, meaning a piece of base metal plated with a thin gold coat. 14K G.F. indicates it's gold-filled made by joining a base metal to a gold layer as in rolled gold plating.
The hallmark convention's work is to facilitate the trade of precious metal items, maintaining fair trade and consumer protection. It introduced the Common Control Mark as an international standard to indicate the type of precious metal and its purity.