While the timing has pretty much stayed the same, there's one major aspect of engagement season that has evolved in recent years: Engagement rings no longer have to cost an arm and leg. According to Metro , the traditional rule that "an engagement ring should cost an equivalent of three month's salary" is officially passé. "The idea of the engagement ring now, I feel, is more tied to values and integrity of the material and the maker, as well as the people who will ultimately own the rings," Anna Sheffield , an L.A.-based jewellry designer, said in the interview.