I'm not sure what it is worth, but my guess is it will go for around $250-350 depending on how much one values the RB designation. It doesn't have any real distracting carbon spots, but does appear to have a small fingerprint on the reverse. For information a nice light brown coin in 65 sold last year for $200, the 1799 is the most common of the Geo. III dates.
Comments
World Collection
British Collection
German States Collection