Impaired Proof	This refers to a circulated proof, and grades less than PR-60.
Incandescent Light	Direct light from a lamp for photography, as opposed to indirect light such as that from a fluorescent bulb.
Incomplete Strike	A coin that is missing design detail because of a problem during the striking process. The incompleteness may be due to insufficient striking pressure or improperly spaced dies.
Incuse Design	The intaglio design used on Indian Head quarter eagles and half eagles. These coins were struck from dies which had fields recessed so that the devices – the areas usually raised – were recessed on the coins themselves. This was an experiment to try to deter counterfeiting and improve wearing quality.
Indian Cent	The common name for an Indian Head cent.
Indian Head Cent	James Longacre designed cents(1859 to 1909). Coins between 1859-1864 were produced with copper-nickel alloy, and between 1864 to 1909 in Bronze.
Indian Head Eagle	The Saint-Gaudens designed a ten-dollar gold coin struck from 1907 to 1933.
Indian Penny	Jargon for an Indian Head cent.
Ingot	A square piece of cast metal, usually of gold or silver, with weight and fineness, specified used in the production of coins.
Inscription	The legend is struck onto the coin, some coins have an inscription on the obverse, reverse and even the rim.
Intrinsic value	The value of the metal(s) contained in a numismatic item.
Investor	An individual who buys numismatic items strictly for profit. These people do not care to complete a set or particular collection but look at the mintage, scarceness, value and profit ranges.

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