What are the facts behind the tradition of ear piercing?

Usually ear piercing has to be done on 10th, 12th or 16th day after the birth of the child. Or otherwise it has to be done on 6th or 7th months or 5th year or 7th year after birth. There will be a muhurtam set for the ceremony and special puja is done regarding ear piercing. Many of them get their child’s ears pierced with a goldsmith with gold needles. This is because gold never rusts. Baby girls get their left ear pierced first and baby boys get their right ear pierced.