Most tough is made up of patches or veins on the host rock through which it formed, which include chalcedony, opal, brown limonite, black chert, or white kaolinite. Lapidaries normally cut this brownish or black matrix along with the stone to deliver colour contrast and styles. Colorless zircon is known https://www.gemsbiz.com/blog/explore/the-december-birthstone-zircon-tanzanite-turquoise