There is a little bit of exact science and a whole lot more inexact science powering the concept of mood rings, which were launched into the public consciousness as an affordable 1970s jewelry accessory fad.

How It Works...Technically 

The exact part comes from the fact that these hollow quartz or glass vessels contain thermotropic liquid crystals, polymers that change color when heated to different temperatures. The inexact foundation of the mood ring phenomenon relates to the idea that no one has ever scientifically shown an accurate causal link between specific human moods and any of the claims made in mood ring color charts.

When the body temperature of a mood ring wearer's hand increases or decreases perceptibly beyond the standard benchmark of 98.6 degrees Fahrenheit, the color of the polymer may also change. But it will do so irregardless of whether or not the body temperature change relates to mood, sickness, exercise or even external weather conditions.

Why Mood Rings Are Debunked 

As a result, many online discussion threads broaching the topic of mood rings tend to debunk them. For example, if someone gets warm (or flushed) because of anger and another individual experiences a similar if not identical temperature change due to happiness or another emotion, can a mood ring accurately differentiate one state from the other? The substance of mercury iodine, which is a more precise temperature gauge, was used early on in mood rings until health regulations banned that practice. Relatively speaking, mood rings are today a minor novelty item, marketed mainly to children and casual wear fun seekers.