Seems to be silver, maybe pewter (I don't know how to tell the difference). It's about 2.5" x 3" in a bamboo or balsa (very light wood) box with Japanese writing on it
Was purchased for my mother, by my father when they were in Japan in the 70's.
This is a vintage, 20th century hand wrought metal pin brooch of a rose that is from Japan and signed on the front with the artisan's initials W.Y. The brooch, from the images, does not appear to be stamped with an indication of being sterling silver and is more likely pewter than silver. It is however, recommended to have the metal tested for sterling. This can usually be done, at no charge at a gold/silver buyer shop which are in most towns and all cities. The estimate is based on actual recent past recorded auction sales of comparables. Retail 'asking prices' can be higher and vary.