NGC Error Coins & Mint Varieties 3

Question 1

What is a 'cud' on an error coin?

Accepted Answer

A raised lump of metal at the rim area caused by metal flowing into a die break that extends to the edge

Answer

A cud is a raised, unstruck area on a coin—typically at the rim—formed when a section of the die breaks away, leaving a void that fills with metal during striking and creates a raised blob where design detail should be.

Question 2

An 'overmintmark' (OMM) variety is created when:

Accepted Answer

One mintmark punch is applied over a previously punched mintmark letter of a different mint

Answer

An overmintmark variety occurs when a mintmark punch for one mint (e.g., 'S' for San Francisco) is applied over a mintmark for a different mint (e.g., 'D' for Denver) already punched into the working die, with evidence of both letters visible.

Question 3

What characteristic most distinguishes a proof die from a business strike die?

Accepted Answer

Proof dies are polished to create mirror-like fields that contrast with frosted, sandblasted design elements

Answer

Proof dies are specially prepared by polishing the field areas to a mirror finish and applying a sandblasting or acid treatment to the design elements, creating the distinctive 'cameo' contrast seen on proof coins.

Question 4

A 'flip-over double strike' error occurs when:

Accepted Answer

A coin is turned over and fed back through the press, so both faces show design elements from both sides superimposed

Answer

In a flip-over double strike, a struck coin is somehow turned over and re-enters the coining chamber, receiving a second strike that impresses obverse design elements on the reverse (and vice versa), creating a coin with overlapping imagery from both sides.

Question 5

In variety collecting, the abbreviation 'RPM' stands for:

Accepted Answer

Repunched Mintmark, where a mintmark was punched more than once into the die at slightly different positions

Answer

RPM (Repunched Mintmark) describes a die variety where the mintmark punch was applied to the die more than once with slight positional differences, leaving visible traces of the earlier punch position on struck coins.

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NGC Error Coins & Mint Varieties 3