TURKEY: Mahmud II, 1808-1839, AV rubiye (0.80g), Kostantiniye, AH1223 year 7, KM-608, AU, ex Ahmed Sultan Collection. The rubiya ("quarter") is ¼ of the sultani (findik), which was struck to the standard of about 3.50g until reduced to 3.20g under Mustafa IV. Thus this rubiya is exactly ¼ of the reduced sultani. It is not ¼ of the zeri mahbub, which weighed about 2.60g, even though this classification has been almost universal in the KM and other catalogs. It should correctly be called ¼ sultani, ¼ findik, or ¼ eshrefi (three different terms for the same denomination).
Estimate: USD 75 - 90