Articles made out of precious metals are usually assayed before they are put up for sale. This is done in order to determine the amount of pure metal in the article. Silver articles may be made out of an alloy of Silver and some other metal to give it strength. Different marks may be used for indicating the fineness of the metal, maker of the article, country and year of assay. The Silver from different countries may be distinguished by its fineness. A Silver standard is followed in many countries for determining the fineness of Silver in an article. The decimal system where a decimal number indicates the quantity of Silver in parts per thousandth is commonly used.
Niello is a black alloy of Silver, Copper and Lead Sulphides. It is commonly used to fill engraved metals. Designs are etched on the surface of the metal, usually Silver, and Niello is used as an inlay. Nielloware or jewellery also known as Siam Silver jewellery are collectible items. It is also known as Thai jewellery.