from the Antique Jewelry University
.800 purity mark incorporated in a Swiss maker's mark. Silver watch case, first quarter of the 20th century
.800 silver is an alloy of silver that is 800 parts silver 200 parts other metals. It is also referred to as International Coin Silver. This alloy was common on 19th and early 20th century European mainland but is not used in jewelry in the United States. 800 silver was the alloy of choice for pieces decorated with
niello because it can withstand firing temperatures better than alloys with a higher silver content.
