> We exchange diamond rings as part of the engagement process because the diamond company De Beers decided in 1938 that it would like us to. Prior to a stunningly successful marketing campaign, Americans occasionally exchanged engagement rings, but it wasn’t pervasive. Not only is the demand for diamonds a marketing invention, but diamonds aren’t actually that rare. Only by carefully restricting the supply has De Beers kept the price of a diamond high.
Imho, that "soul" you describe is an artifact of human sentimentality and a very successful marketing campaign by a bunch of Afrikaner colonialists.