Modern commemorative coins are a type of collectible coin issued by the United States Mint to honor historic events, people, or places. The $5 gold coins, referred to as G 5, were introduced in 1986 and have gained popularity for their limited mintage and aesthetic design. The 1991 commemorative coins specifically celebrate the 250th anniversary of the founding of the city of San Francisco, featuring unique designs that reflect the city's heritage. These coins are composed of a specific gold content and are sought after by collectors for both their numismatic value and historical significance.