Kate Middleton doesn't always wear the sapphire and diamond engagement ring that was once worn by her late mother-in-law Princess Diana, and there is a standout reason why.

Everything you need to know about the engagement ring finger—from where it is on your hand to the sweet history of the tradition.

Her engagement ring—which she paired with a Welsh gold wedding band, a marital tradition for the royals—features a rare pink-orange padparadscha sapphire as its centerpiece with a diamond ...