The 1853 BG-604 Gold Dollar is one of the most desirable of all the California Fractional Gold pieces. It is certainly, the most valuable. Jay Roe paid a reported $100,000 for the best of only two known examples. When Roe's collection was sold in 2003, the coin realized $80,500. In 2005, the coin resold for $82,800, and it would probably be worth over $100,000 again today.
The obverse of this variety features a Liberty Head facing left; the initial's "G.G." beneath the bust stand for Gaime, Guillemot & Co., for whom the coin was made by Frontier, Deviercy & Co. The unique reverse of this variety has an unusual, fatty eagle with a crest atop its head resembling that of a cockatoo. This is the only round Dollar with an eagle on the reverse.
The only other example known to exist shows the details of an About Uncirculated coin, but it has a small patch of heavy scratches in the left obverse field opposite Liberty's eye. That coin, which had been off the market since 1956, reappeared in the January 2016 Heritage auction.
Plate coin in Breen-Gillio, second edition (2003)
Superior 9/1987:4487 - Goliad Corp, sold privately on 8/26/1991 via Mike Brownlee for a reported $100,000 - Jay Roe Collection - Bowers & Merena 9/2003:137, $80,500 - American Numismatic Rarities 7/2005:20, $82,800
Believed to be ex F.C.C. Boyd Collection - New Netherlands Fixed Price List of July/August 1957:5194, $225
Possibly John W. Scott, possibly A.G. Heaton (per the Heritage 1/206 catalog) - Waldo C. Newcomer Collection - T. James Clarke Collection - New Netherlands 4/1956:683, $200 - Donald R. Hyink Collection - Elbert Henry Gary Collection - Heritage 1/2016:5730, $82,250