The largest of the Japanese gold coins. It is oval in shape but variable in size, some specimens being six inches in length, and weighing over five ounces.
The face of this coin is usually covered with symmetrical lozenge shaped flutings, and it is stamped at the ends and sides with the Government crest of the day, namely, the Kiri flower and leaves. The value, usually about ten Ryo, is painted in Japanese ink on the face by the superintendent of the mint.
The Oban came into use A.D. 1573-1592, and was issued until about 1860. For the many varieties conf. Munro (p. 188 et seq.).
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)