Alloy: A mixture of two or more metals combined to enhance the strength and/or appearance of a coin.
Bag Marks: Marks or nicks on the surface of a coin typically caused by contact with other coins in a mint bag.
Brilliant Uncirculated (BU): A coin that has never been circulated and retains its original mint luster, but may have minor imperfections.
Clad Coin: A coin that has multiple layers of metal. For example, modern US quarters and dimes have a core of copper and an outer layer of a copper-nickel alloy.
Die: A metal stamp used to strike the design onto a blank coin.
Edge: The outer border of a coin, considered the “third side” (not the obverse or reverse), which can be plain, reeded, or decorated.
Field: The flat background surface of a coin against which the design is set.
Grade: The rating of a coin’s condition, based on its level of preservation and the visibility of its original minting detail.
Key Date: Typically the rarest (and often most valuable) coin in a particular series, often due to low mintage or survival rate.
Legal Tender: Coins that are officially recognized by a sovereign government as valid for meeting financial obligations.
Mint: The facility where coins are manufactured.
Mint Luster: The original sheen or shine of a coin, which is a result of the minting process.
Mint Mark: A small letter or symbol on a coin that identifies the mint where the coin was produced.
Mintage: The quantity of coins produced during a particular time frame at a particular mint.
Numismatics: The study or collection of currency, including coins, tokens, paper money, and related objects.
Obverse: The front or “heads” side of a coin, usually featuring a portrait or primary design.
Patina: A thin layer of tarnish that forms on the surface of some coins, often seen as a desirable form of toning due to aging.
Proof: A coin that is struck with a special process that involves multiple strikes with specially prepared dies and planchets to produce a high-quality finish with a sharp, mirror-like surface and frosted details.
Reeded Edge: A coin edge with grooved lines all around, which is common on many coins, like the US quarter and dime.
Relief: The part of a coin’s design that is raised above the surface.
Reverse: The back or “tails” side of a coin, which typically carries the denomination if one is present.
Slabbed Coins: Coins that have been graded and encapsulated by professional grading services in sealed protective plastic holders.
Toning: The discoloration or change in color of a coin’s surface due to chemical reactions with external agents, which can be natural or artificial.
Uncirculated: A coin that has never been put into public circulation and therefore shows no signs of wear.