This is a not-terribly old, very interesting article from Slate on the history and subtext of engagement rings, and engagement rings are what we're talking about here. (Wedding bands are another story, and I really do think they should have all new bands for that.) Unfortunately, diamond rings are still seen as status symbols by both men and women, and the commonly accepted practice is that men wear their (generally plain gold) wedding band, while women continue to wear their engagement rings throughout the marriage. The hidden message behind engagement rings is, "This woman is bought and paid for." What LW's fiance is saying, symbolically, if you will, is that she "paid" for herself. She is independant and secure and is STILL willing to partner herself to this wimp. I'll agree that recycling diamonds is odd, but clearly, it means something to her. If LW is a traditional type of man, well, he needs to know that she's a very clearly non-traditional type of woman. "Traditional" in this case meaning that he likes the idea of a woman with either no past or the ability to utterly reject her past. "Non-traditional" meaning that she accepts that there is both good and bad in her past, that she chooses not to forget it and instead to learn from and adapt her past to her future. If the diamond has any real symbolism here, it symbolises HER. The new setting should, quite literally, symbolize her transition into a new life. Not entirely unchanged, but definitely not exactly what she was before.