1916C Ottawa Sovereign
Although not the lowest mintage Canadian sovereign, the 1916C sovereign is one the rarest Canadian sovereigns. The reason for its higher than expected rarity is not known, but it is widely accepted that most 1916C sovereigns were melted for their gold content during or after World War I: a similar fate befell many other 20th century sovereigns so it seems plausible that the same occurred for the 1916C sovereign.
More recently is has been reported that the Bank of Canada sold a reserve of sovereigns to dealers by private tender - presumably including a number of 1916C sovereigns. This sale was apparently after and separate to the 2014 Bank of Canada sale of its reserve of 1912-1914 $5 and $10 coins.
While the entry of previously unknown 1916C sovereigns to the market cannot be proven, previous estimates of extant coins have been around 50, and third party grader population reports are now close to that figure. While population reports might include duplicate coins, they are moderately indicative, as the high rarity of a 1916C sovereign makes resubmission a largely pointless exercise as the coin's value is mostly due to its rarity rather than its condition.