im not sure. but in the فلمیں bells wears alot of rings. they are jsut trying to trick us. that and we dont know which meadow scene this is in the book,.... cause one stage of the meadow she is wearing it and others she is not.. sooo
It is her engagement ring. It's already been confirmed.
The ring is supposed to be Edward's mother's, so it is old fashioned. I don't personally like it, however, the تفصیل in the book is what this looks like. Stephenie Meyer has even گیا کیا پوسٹ on her website what Bella's ring looks like.