Sam: Where in the Seforim HaKedoshim, prior to the de Beers diamonds-are-forever marketing campaign, has engagement rings (not wedding/chupa rings) been mentioned as a minhag and among which communities?
What Judaism certainly has contributed to societal wedding practices is the white kallah dress.
“The engagement ring will probably be nicer than the previous ring.”
PAA: Like her possibly wanting a nicer ring, he might want a nicer Shas with more meforshim.