a town of Germany, in the principality of Birkenfeld, belonging to the grand duchy of Oldenburg, on the river Nahe, 33m. S.W. of Kreuznach, by the railway to Miinsteram-Stein. Pop. (1905) 9669. It is famous for the cutting and setting of agates and other precious stones, an industry which has been established here, and in the neighbouring township of Idar, since the 16th century. The Evangelical church, built in the 12th century and restored in 1482, is partly hewn out of the solid rock. On the hills above the town are the ruins of two castles.
See Hisserich, Die Idar-Obersteiner Industrie (Oberstein, 1894).