Click image to view full size image
Pink aluminum oxide grinding wheel is one grinding wheel among many others, and the main ingredient of it is alpha-alumina, also known as pink fused alumina, artificial ruby, which can be seen that how hard it is.
link:https://www.renwa-abrasive.com/vitrified-grinding-wheel/pink-aluminum-oxide-grinding-wheel.html
Pink Fused Alumina Grinding Wheel