I am an avid metal detector user and am studying up on some of the industry terminology as I prepare to get some of the items I have found refined. For example, what is meant by “gold filled”, “troy ounce” and “pennyweight.” — Rick in Louisiana, MO

Thank you for you inquiry, following are some of the common terms used in the precious metal refining industry.

Carat – a unit of weight for gems
Karat (K, kt) – is measure of purity for gold
Fineness – the proportion of pure precious metal in an alloy, often expressed in parts per thousand
Fine Weight – the metallic weight of a coin, ingot or bar
Gross Weight – the total weight of an item, including the alloying metal
Gold Standard – a monetary system in which a region’s common medium of exchange are paper notes that are normally freely convertible into pre-set, fixed quantities of gold
Hallmark (plate mark) – an official mark or stamp indicating a standard of purity, used in marking gold and silver articles.
Luster – a substance, as a coating or polish, used to impart sheen or gloss
Ounce – a unit of weight. In the precious metals industry, an ounce means a troy ounce equal to 31.1035 grams
Spread – the difference between the buying price and the selling price of a precious metal
Troy Ounce – a unit of weight equal to 480 grains or 1/12 of a pound
Grain – the smallest unit of weight
Face Value – the nominal dollar amount assigned to a security by the issuer
Retail Value – the sale of goods or articles individually or in small quantities directly to the consumer
Pennyweight (dwt, pwt, PW) – a unit of mass which is the same as 24 grains, 1/240th of a troy pound, 1/20th of a troy ounce, approximately 0.055 ounces or approximately 1.555 grams
Hardness (HV) – sometimes called “scratch resistance,” the Vickers Hardness scale tests hardness of a metal by pushing a pointed object into the surface with a specific load and gauging penetration
Metal – any category of electropositive elements that usually have a shiny surface; typical metals are from salts with non-metals, basic oxides with oxygen and alloys with one another
Salt – crystalline chemical compound formed from the neutralization of an acid by a base containing a metal or group acting like a metal
EPNS – electroplated nickel silver or silver plate
Gold Filled (G.F.) – an item that has a thin outer layer of gold over a base metal. Items must be at least 1/20 gold by weight to be called gold filled
Gold Rolled (R.G.P) – Popular during the 19th century where a very thing sheet of solid gold is laminated to a lesser metal then fused together
Gold Plating – also referred to as electroplate (GEP), is a process where one metal is coated with another metal using electricity
Pinchbeck – gold substitute made with a combination of 9 karat gold, copper and zinc
Vermeil – usually gold plated sterling silver

Are there any precious metal terms we left out that you would like to know?