For anyone who came of age in the '70s or '90s, mood rings were more than a colourful accessory — they were supposed to reveal the wearer's true emotions with the help of a simple, colour-coded key.

Mood rings were one of the biggest fashion fads during the 1970s — touted as having the ability to "identify" the mood of the ring wearer by a corresponding color. During that decade, as people were ...