Goldstone is a kind of glittering glass that is made in a low-oxygen reducing atmosphere. Goldstone is man-made. It can either be a reddish-brown color or a dark blue. It is a Goldstone is a semiprecious gemstone. Another name for it is adventurine glass. Reddish goldstone is copper-based. Non-copper goldstone, such as blue goldstone, which has cobalt, are easier to work with than reddish goldstone. Goldstone is sometimes called sandstone, a sedimentary rock, and it is used in watches.