ured by weight. No gold alloy of less than 10 karat quality may have a karat mark applied to it.

Nickel Silver: A base-metal alloy of silvery color. A typical composition is 65% copper, 18% nickel, and 17% zinc.

Osmi: An abbreviation for osmium.

Osmium: A metallic element and one of the six platinum metals.

Pall: An abbreviation for palladium. Palladium: A metallic element and one of the six platinum metals.

Plat: An abbreviation for platinum. Platinum: A metallic element and the principal metal of the platinum group.
Platinum Metals: A group of six elements usually occurring together-platinum, palladium, rhodium, ruthenium, iridium, and osmium.

Precious Metals: Silver, gold and the six platinum metals-platinum, palladium, rhodium, ruthenium, iridium, and osmium.

Quadruple Plate: A silver coating having

an average thickness four times that of "Standard Plate."

RGP: An abbreviation for Rolled Gold Plate.

Rhod: An abbreviation for rhodium.

Rhodium: A metallic element and one of the six platinum metals.

Rhodium Finish: A term used to describe the brilliant finish obtained with a thin layer of rhodium applied to other metals by electroplating.

Rolled Gold Plate: A composite metal of base metal coated on one or more sides with karat gold alloy. For jewelry, other than watch cases, the proportion of karat gold may be less than 5% of the weight of the composite metal. For watch cases, the karat gold coating is required to be at least 0.0015 in. thick.

Ruth: An abbreviation for ruthenium. Ruthenium: A metallic element and one of the six platinum metals.

Sheffield Plate: A composite material, made originally of copper coated with a layer of silver, applied by a fusion process discovered in 1742. Commencing around 1830, a white