Which is harder, white corundum or brown corundum?

Which is harder, white corundum or brown corundum?
The hardness of corundum is actually determined by the content of alumina. The higher the content, the higher the hardness. The alumina content of white corundum is ≥99.5%, and the content of brown corundum is ≥94.5%. Therefore, the hardness of white corundum is greater than that of brown corundum and white corundum. The Mohs hardness of brown corundum is 9.0, and the Mohs hardness of brown corundum is slightly lower than that of white corundum.