A very interesting and unique find!!!
Gold coins are rarely seen that have been smoothed on one side, and jeweler engraved. The practice of jeweler engraving, was indeed quite popular on silver coinage during the later half of the 19th Century. Gold coins however, being of considerable more value, were rarely relegated for these mementos. The remaining solder marks on the one side of this item above, surely attest to being originally affixed to a display piece of jewelry.
The details on the 1856 dated side of this piece, featuring a head with
LIBERTY on the band, match with great precision to the Coronet Type gold coins minted in the United States from 1840-1907. Comparing the details on the head side of the engraved piece above, with the details on the standard mint issue 1856 $2.50 gold coin in the photo provided below here, we see a match with all design features and positioning. The smallest of the Coronet Type gold coins, the $2.50 denomination, had an original weight and diameter of 4.18 grams and 18 mm respectively. With a description of about 9/16" diameter in the beginning post (translating to about 14.2 mm), we would however not have a match to a $2.50 Coronet Type gold coin. The diameter as described at 9/16" would indeed be closer to a $1.00 gold coin of 15 mm, yet we may note as well (as has been pointed out in a previous post), that the design on a standard U.S. mint issue $1.00 gold coin of 1856, is entirely different. The standard U.S. mint issue gold coins of 1854-1889, all feature an Indian Head Type design, as well as having other details such as
United States of America on the obverse (face side), and no date (the date is on the reverse or back side). At this point, I suspect that original measurement as described of "about 9/16", was not precise, and we may in fact be dealing with a true $2.50 gold coin that more closely matches the measurement of near 11/16" diameter.
The possibility of a Private Mint gold coin can surely be ruled out, as there is only the isolated examples of a $2.50 gold coin featuring a Coronet Type head, along with LIBERTY on the band, with that being the Clark, Gruber & Co. coins of Denver Colorado dated 1860. The small denomination California fractional gold pieces, of $0.25, $0.50, and $1.00, produced at first privately to supplement commerce demand for small currency, and primarily later as tourist and novelty pieces, are known in some examples to feature a Liberty Head design, yet the die work and detail in these pieces is not even close in quality to what we see in regular issue coinage.
The observation by Surf, that the engraved detail on this piece, appears to depict an Oil Well scene is a valid point that I certainly concur with. The fact that Pennsylvania was host to our first great Oil Boom, coincides as well with general location and time frame of this unique gold piece.
Pennsylvania oil rush - Wikipedia, the free encyclopedia
CC Hunter