Chemistry of Mood Rings

Quick Facts

• Invented by Joshua Reynold• Popular fad in the 1970’s • Still around today• The stone of the ring changes color

supposedly in response to the mood of the wearer

How They Are Made

• Stone: hollow quartz, glass, or a coating of some kind, containing thermotropic liquid crystals

• Ring: usually made of sterling silver, or a coating of silver over another type of metal

• The liquid crystals are glued on the ring and coated in order to seal out moisture which may spoil the ring

How They Work

• The thermochromatic liquid crystals respond to external body heat

• The crystals absorb the energy generated from our bodies

• They twist in response to the energy, altering the way that light passes through them.

• Causes the crystals to reflect different wavelengths of light which changes the color

Colors

• Violet Blue – warmest• Blue – (about 82 degrees F)• Green• Yellow/Amber• Brown/Gray• Black – coldest (sometimes means the ring is

damaged)

Thermochromatic Liquid Crystals

• A liquid crystal is thermochromatic if the property of the components change color due to temperature

• Do not emit light directly• High energy: isotropic liquid phase• Twisted nematic phase: light passing through the

crystal undergoes Bragg diffraction in this phase• anisotropic chiral phase• Low energy: glass(crystallic) phase

Phases

Other Uses for Thermochromatic Liquid Crystals

• Liquid crystal thermometers• PDLC smart windows• Hypercolor t-shirts• Liquid crystal display (Television Screens,

Computer Screens, Digital Alarm Clocks, Scientific Calculators, etc…)

Liquid Crystal Thermometers

PDLC Smart Windows