The main differences between white corundum, brown corundum and black corundum are as follows:
Color
- White corundum: white and transparent.
- Brown corundum: brown-black, brown-red, crimson, etc.
- Black corundum: black with metallic color.
Alumina content
- White corundum: aluminum oxide content ≥99.2%, the highest among the three types of corundum.
- Brown corundum: 94%≤alumina content≤75%.
- Black corundum: 45%≤alumina content≤75%, relatively low aluminum oxide content.