How big is the needle they use to pierce the cartilage in your ear?

Well that depends on the size of the jewellery being used in the cartilage. Cartilage piercings are never to be done with a piercing gun for obvious reasons. The needle is over gauged which is to say it's one size bigger than the jewellery going into the piercing. This is to allow the tissue to heal around the exposed cartilage and allow for a clean heal between the jewellery and cartilage. This is not a do it your self piercing, serious infections and permanent damage can result due to lack of knowledge of the human body and it's structures..