Honestly when I first read about teething necklaces I thought the child must chew them. I hesitated thinking what a choking hazard! You know the child isn't supposed to chew the necklace at all, they simply need to wear it against their skin.
Caspar wore his infrequently and it didn't appear to help at all. However Otis is happy to wear his all the time. He doesn't notice it and you cannot even see it, it's usually hidden beneath his clothes.
The theory is Amber has healing properties and can help relieve the pain of teething. The Amber needs to be warmed against the skin. There is no possible harm in wearing the necklace (it has a release on the clasp so it will break if it gets caught) and nothing else has helped. Gels, paracetamol, teethers still no relief. I like to think the Amber is helping in the most natural, soothing way.