Top 25 "It" products of all time: #16 -- The Mood Ring

The mood ring may be far out, man, but it has a practical, medical history. The ring was conceived in the 1960s, when Marvin Wernick went to an emergency call with a doctor friend, and watched him use a thermotropic strip to take a child's temperature. Aha! He thought. Jewelry!

Strange but true. Wernick got some thermotropic paper and fitted ovals of it into rings with glass "gemstones" to show off the color. He wrote up some incredible claims about the connection between body temperature and mood, and a new psychological accessory was headed toward American history.

In the late 1960s, the rings came into wide production, and soon were known as a symbol of the 1970s, changing from dark blue (happy! and passionate) to green (average) to amber (a little nervous) to gray and black (stressed out, man) as the bell bottoms changed from wide to enormous.