A Golden Error

A mint expert has confirmed the existence of a significant error on a well-known South African bullion coin. The 1998 1-ounce gold proof krugerrand is supposed to have 220 serrations on its edge, and the error has a serration count of 179-180. 

Dr. Mike Gradwell, who used to work in executive manufacturing support and development at the South African Mint, investigated the claim and confirmed the error. He believes it likely occurred when “the wrong collar was used, i.e., a bullion collar instead of a proof collar.” 

Dr. Gradwell estimated that, assuming the incorrect collar was used for an entire shift, up to 100 of the 2,000 proof krugerrand produced could have the incorrect number of edge serrations. However, since the error is undocumented, the actual survival rate is unknown. Currently, only two are known to exist.