The mood ring was created in 1975 by New York inventors Josh Reynolds and Maris Ambats. They initially retailed at $45 for a “silver” setting or $250 for a gold setting. The rings were first sold at Bonwit Teller, a New York City department store.
The mood ring is a specialized liquid crystal thermometer that is said to indicate the emotional state of the wearer. The ring contains a faux gemstone (usually of quartz or glass) and either contains a capsule of thermochromic liquid crystal or is lined with the thermochromic crystal. Temperature changes cause the crystal to reflect different wavelengths of light which in turn change the color of the gemstone.
Theories say that body heat causes major changes to the ring, but, in fact, the air temperature has a more direct impact. Maybe that explains why the rings revert back to their “neutral” color after a few days and never change again!
Mood rings were very much a mid-70s fad, although they are still available for purchase for today.