Tungsten carbide rings cannot be cut off in emergency situations, such as when a finger swells due to injury. This is because tungsten carbide is an extremely hard and dense metal that can only be scratched with a diamond or other similarly hard materials. While this hardness makes tungsten carbide rings very durable and scratch-resistant, it also means that they cannot be easily removed in emergency situations. For this reason, it's essential to ensure that a tungsten carbide ring fits properly before wearing it regularly.