Barry Sunshine, a collector of California Fractional Gold coins and a student of the series, has this to say about the BG-401:
BG-401 is a round half dollar and is believed to be one of the earliest California Fractional Gold coins made. BG-401 is a Rarity 3 with about 300 to 400 known to exist. Finding a high grade example is not very difficult. Researchers believe that the jeweler, Joseph Brothers, deliberately made it look very similar to a U.S. Type One Gold Dollar so that it would be more acceptable in circulation.