Gold jewelry in Portugual must by law be 19.2 karat pure, there fore the marking of 800 translates to 80% gold, or 19.2 parts out of 24 (24 parts being 24 karat gold, 100% pure). A lot of European gold jewelry is marked 750, which ranslates to 75% gold content, or 18K, 18 out of 24 parts gold. Gold in the US is typically 14K or 58.5% gold, which is represented by the mark 585, 417 is 10K, 41.7% gold. Hope this helps.