I will be adding links to most all gemstones used for cabochons on the page as I find time.
You will find information on some of the most often seen material like ocean jasper and agates, as well as some you very seldom see offered in cabochons and collectors stones like marra mamba, blue dot chryscolla, binghamite, covellite, gem silica, fire agate, chalcocite with chrysocolla and many others.