#8125-12 is in most respects a catalog-standard TB-3 Mastertone dating to 1925 (see Gibson banjo serial numbers vs. factory order numbers); the gold plating is a later modification. Close inspection of the peghead reveals a quirk of prewar Gibson banjo production. The peghead overlays were inlaid with mother-of-pearl, then completely covered in black stain. The dried stain was scraped off of the inlays, resulting in a clean appearance and helping to hide filler which might have been used; the smaller diamond in the center of the four larger diamonds was never uncovered on this example, but its outline is visible underneath the stain.
#8125-12 remains in its original #509 case by Geib and Schaefer. The longtime (and possibly original) owner of this banjo was George T. Brown of Grand Haven, Michigan.
Photos courtesy of Dave Hallock.