Tourmaline's hue and depth of color can approach the range of ruby and pink sapphire. Many gemstones change their colour depending on the light source. A true rubellite does not. It shines just as intensely in artificial light as it does in daylight. The colour of most other pink or red tourmalines, by contrast, displays a more or less clearly visible tinge of brown in artificial light.
红色桃红都算rubellite，但是在人造光源下，不能有棕色调，我查到的是这样的解释。