KINGS of LYDIA. temp. Cyrus – Darios I. Circa 550/39-520 BC. AR Siglos (17mm, 5.14 g). Kroiseid type. Sardes mint. Confronted foreparts of lion right and bull left; c/m: three pellets within conforming incuse / Two incuse square punches. Berk 22; SNG Ashmolean 762–71. Toned, typical granularity, irregular flan with unusual ridge around edge. VF.
While the obverse and reverse appear completely normal, and there is no indication of the piece being a fourrée, the ridge around the edge of the fln has the appearance of the edge of metal plating. However, under magnification, the metal appears to be contiguous; that this is not a "seam" that is indicative of forgeries (ancient and modern). The only possible explanation seems to be that the mint used an irregular flan that had an unusual feature around the edge that resulted in this odd effect on the struck coin.