In diamond ads, it always seems to me that the woman is in love with the diamond. Maybe I'm being cynical.
Well, they did flip "Show her you'd marry her all over again." Where I come from (Catlick bacground) that means renewing your wedding vows in a religious ceremony. They made it into giving her a big rock for her finger.
In love with a man, in love with a rock... whatever... a woman in love is very attractive. And when all you see on TV is women in heat, it gets your attention very well.