Watch List notes:

Large tumbaga gold ingot, 1816 grams, marked with fineness V and three dots (5.75 karat, or 23.96% fine), also marked with R and S and several tax stamps of Charles V, Holy Roman Emperor, ex-"Tumbaga wreck" (ca. 1528), Garcia-Barneche Plate. Approx. 12-1/2" x 2" x 1". This the largest and arguably most significant of the very few GOLD ingots found on the "Tumbaga wreck," which is the only known source of such ingots, all of which are very low in fineness (marked between 5-3/4 and 8 karats). Of the thirteen pieces known, all but two are cut down in their time, the intact two being a long and skinny rod and the present lot, which is somewhat club-shaped with a wide diameter and one end bulbous, the rounded bottom showing small marks of fineness V (incuse) and three dots in a column immediately followed by an S-shaped mark in a box plus a single dot in a box, the flat top of the bar showing four partial tax stamps (which show parts of CAROLVS IMPERATOR) and one mark with an R in a box (formerly seen as a B). The meaning of the S and R marks is not known. The top of the bar also shows several patches of encrustation, including both dark oxidation (from leached-out copper) and lighter (greenish) coral adhesion. The bottom shows a couple of mold-cracks (raised lines), next to which some lighter encrustation has accumulated as well. A typically sharp assayer's "bite" (also encrusted) is cut from the smaller end. The overall color of the ingot is very brassy, which is to be expected for an ingot of such low fineness; but XRF analysis on this piece reports it as about 39% gold, 56% copper and 5% silver, a fineness (9.32K) that exceeds what is marked on the bar itself (5.75K) by over 60%! Curiously, the exposed metal in the "bite" at the end shows more of a gold color, leading us to speculate that the surface was purposefully tinted to pass off a fraudulently low assay. In any case, this bar and its shipmates are true tumbaga in that they were made from native artifacts created from a mix of copper and gold. Also, as postulated in Garcia-Barneche, these tumbaga gold bars were probably made and loaded onto the ship in Santo Domingo or Cuba, as opposed to the silver "tumbaga" bars whose origin is now known to be Michoacan, Mexico. From the "Tumbaga wreck" (ca. 1528), with photo-certificate, pedigreed to the Christie's (London) auction of April 28, 1993 (lot #297), and plated on pages 66 and 68 of Agustin Garcia-Barneche's The Tumbaga Saga, 2nd edition (2018), a copy of which accompanies the lot.
($35000-70000)