I just found a mage amulet and I want to turn it in to the mage, but I'm not sure what I'll get in return. Does anyone know?

You can turn them in to either receive a shard or a tome. ( or etc.) I believe you are more likely to get shards over tomes.

Tomes will increase your pet stats and shards are...useless, I guess. It's up to you.

It's a risk... well, I suppose I have no use for the amulet anyways. :I