Stop using immediately if the glass is either broken or cracked on impact. Take care that the sharpening slurry is not left on the stone after using otherwise it maybond with the stone on drying. Take care that glass stones are not kept in water.Otherwise it will greatly shorten the durability of the stone. Avoid storing in the places which reach high or low temperatures. Extreme temperatures will cause cracking. Take care that glass stones are not placed in a location subject to direct sunlight. The stones may get weathered and cause cracking. Take care that glass stones are not dried rapidly with fan, drier, etc. This will cause breaking or cracking.Take care that hot water is not put on glass stones. This will cause breaking or cracking.Take care that detergent is not used for glass stones. This will cause loss of sharpening capability.