The Victorians called these 'Scots Pebbles', and the original fad for them was English; Queen Victoria summered in Scotland, where she wore kilts (of a sort) and local jewelry to support indiginous industry and crafts. But they were, I suspect, made and worn everywhere. This lovely agate brooch measures 1.5" by .75", is in its original rose gold fill bezel, but has had a safety clasp added. Minor wear on the gold fill, otherwise perfect. ca. 1860s.