Gold Test Premium stone. A high quality premium testing stone essential for testing Gold, Silver, and Platinum. It is black in colour for great contrast. A test can be made with one light strike leaving no scratch marks on the item being tested which is a big advantage when testing non scrap items. It is designed specifically for testing, leaving a very visible streak when testing Gold, Silver, and Platinum and it will not damage the pieces you are testing. This brand new stone has a rubber backing plus it is a high quality testing stone that can be washed and used again for hundreds of tests. 5cm x 5cm or 2" x 2". Made in USA.