A kallah without a diamond ring is like a chosson without a diamond ring. Some are machmir on the kiddushin ring as well.
I tell all of my sons-in-law that if they want me to buy them a chosson shas, they have to buy one for me as well. Sure, I’m supposed to marry my daughters off to talmidei chachomim, but they’re also each supposed to marry a bas talmid chacham!