Letter I

Impaired Proof

A proof which has numerous hairlines or has been mishandled or abused.


Sunk below neighboring surfaces (intaglio). Gold Indian Quarter Eagles and Half Eagles (1908-1929) are the only U.S. coins that feature an incuse design.

Indian Head Cent

U.S. copper coin (1859-1909). Common name for the Longacre design of cent.


A bar of metal used for the production of coins.


An increase in both money supply and available credit.

Intrinsic Value

The actual value of the precious metal(s) in an item

Inverted Market

See Backwardation


A person who commits capital in order to gain financial returns

IRA Eligible

Items that are approved for addition to a precious metals portfolio, for use during retirement.


A desirable form of toning on a silver or nickel coin. Iridescent toning covers virtually all of the coin’s surface, while still permitting the coin’s natural luster to shine through with its full intensity. Some numismatists feel that in order for toning to be called iridescent, it must have all the colors of the rainbow, or at the very least, most of them.