Look for a small etched or printed mark in a corner that says “tempered” or “safety glass”
Check the edges for a smooth, polished finish rather than sharp cut edges
Compare the glass to nearby pieces for slight distortion or waviness
Use polarized sunglasses or a polarized filter to look for stress patterns
Observe whether the glass is used in places that typically require tempered glass, such as shower doors, car side windows, or glass tabletops
Tap the glass gently and listen for a higher-pitched ring compared with non-tempered glass
Examine the glass for tiny surface imperfections or roller-wave patterns
Check manufacturer labels, stamps, or documentation if available
Do not try to cut, drill, or break the glass to test it
Ask a professional glazier or glass shop to confirm it