100 Dollars - Elizabeth II 4th Portrait - Longest-Reigning Commonwealth Monarch - Gold Bullion Coin

Issued to mark Elizabeth II surpassing Queen Victoria's reign length on September 9, 2015 — the date she became Britain's longest-reigning monarch at 63 years and 216 days. The Perth Mint released this one-troy-ounce piece as part of a broader commemorative program that year, timed to the milestone rather than any standing annual bullion series.

Ian Rank-Broadley's fourth portrait, used on this issue, was already being phased toward replacement by Jody Clark's fifth effigy, which had been adopted by the Royal Mint earlier that same year.