This piece comes from the Royal Canadian Mint's push into five-nines (.99999) purity gold, a standard the RCM pioneered commercially and used to differentiate its fractional bullion products from competitors' standard .9999 fine issues. Achieving that fifth nine requires an additional refining stage that most sovereign mints don't bother with for coins at this weight.
This piece comes from the Royal Canadian Mint's push into five-nines (.99999) purity gold, a standard the RCM pioneered commercially and used to differentiate its fractional bullion products from competitors' standard .9999 fine issues. Achieving that fifth nine requires an additional refining stage that most sovereign mints don't bother with for coins at this weight.