> Many jewelers were confused and incredulous when we asked about one.

Bear in mind that it is in the jeweller's interest to perpetuate such superstitions as it means they can persuade many customers to buy a new ring instead.

Buying a diamonds as a romantic gesture, the buyer is vulnerable for two reasons:

1) They're unlikely to have much experience of buying jewellery; for many, this is the only occasion.

2) They probably feel very strongly about the gesture; it's very important that they get it right. Overspending pales beside the risk of offending the love of their life and/or subjecting them to negative judgement by their peers.

As a result, it is all too easy for jewellers to intimidate the buyer by telling them exactly what is 'expected' and charging absurd prices for it.