I've never tried biting mine either! There are a couple of ways to test if it's real amber or plastic:
If you dissolve as much salt as you can in a glass of water, amber will float.
If you heat a needle up and stick it into/onto it, plastic will smell nasty but amber will smell sweet like pine trees. Do that in a hidden place!
Amber won't be affected by a solvent like nail polish remover but plastic will either go tacky or the solvent will go the same colour as the plastic.
If you rub it with a cloth, amber will become statically charged and you should be able to use it to pick up tiny bits of paper or fluff.