Can you put any earring into a cartilage piercing?

It's not a good idea, especially if your cartilage has been pierced with a larger gauge. It can cause what most people call the "cheesecutter" effect and cut the skin of your ear, causing the piercing to get infected or close up altogether. Another thing to be cautious about is the material the earrings made of as most are shoddy costume jewellery. Your best bet is to buy a high quality piece from bodyartforms.com or somewhere similar.