What are those tiny hairline crack on the surface of granite?

Granite has natural fissures which can look like tiny cracks but are not structural defects. These are naturally occurring result of the immense heat and pressure that formed the granite. These characters are part of the natural beauty of stone and will not impair the function or durability of the matreial. Remember, granite is from the earth so it’s perfectly imperfect and you cannot expect it to look manmade.