... brown, violet, green, pink, or in a dual-colored pink and greenQuality: Natural, tourmaline rough stoneIdentification: ISO9001:2000MOQ ... -0.040; typically about .020 but in dark stones it may reach .040Pleochroismtypically moderate to strongRed Tourmaline: ... brownBlue Tourmaline: Strong; dark blue, light blueDispersion.017Ultravioletpink stones—inert to very weakFluorescencered to violet in long and ...