7. The ring
With weddings involving abductions more often than not, a 12th century Pope found it necessary to decree that weddings from that point forward would be held in churches, and that people would be allowed to marry only after a reasonable engagement period. Since people needed an engagement symbol, they chose a ring.
These rings weren’t valuable and didn’t have diamonds. The diamond was a 20th century addition, famously engineered by the DeBeers diamond cartel through a prolonged and massive advertising campaign. Their slogan was, ‘A Diamond is Forever.’