Can you gauge your ears without them being pierced?

Using body jewelry that is tapered will help stretch the existing hole in your ear. Regular earrings are extremely thin, but if you play with them enough, you can stretch the skin enough to accept a thicker earring. I would use Neosporin, or some other antibacterial ointment to lubricate the end of your thicker jewelry, and then slowly push it into the existing hole. Don't force it, though. You have to give your skin time to adjust to the thicker guage of jewelry. If it hurts, stop, and put your thinner jewelry back in. Forcing it can tear the skin, or cause a "blow out", where the edges of your existing piercing can literally tear away pieces of skin. Wait 4-5 weeks between each guage, if you want to continue stretching. Heavier jewelry, like anything make of surgical steel, will help stretch your skin faster then lightweight acrylic. And yes, if you take the jewelry out, your ears will go back to normal. I took out my 2 guage tunnels and was able to wear regular earrings within 6 months or so.