PART III. Die Installation Errors:

Mismatched business/proof dies:

1999 $5 and $10 gold eagles struck with unfinished

proof dies (W-mintmark)

Definition: Subtle differences in design details often differentiate dies intended for business strikes and those intended for proof strikes. The accidental preparation of a business strike die as a proof die is a well-known phenomenon. Examples include the 1998-S and 1999-S proof cents with the “close AM” reverse. Proof dies sometimes avoid final polishing and are mistakenly used as business strike dies. The most dramatic recent examples are the 1999 $5 and $10 gold eagles with the W-mintmark.

Shown below is a 1999 $5 gold eagle with the W-mintmark struck with unfinished proof dies. Normally the W-mintmark (West Point Mint) is only used on proof issues.