Mood ring cabochon is acrylic and changes color based on temperature. Oval Cabochon size is 18x13mm (18 mm is a little less than 3/4 of an inch and 13mm is right around 1/2 of an inch).
Ring band is gold plated brass.
Some of the meanings of the colors (sheet with meanings included with ring):
Blue: relaxed, calm
Green:active but not stressed
Gray or Amber: anxious, stressed
Violet: Happy, passionate and romantic
Ring is adjustable from size 6 to 15. After size ten there is a gap but the ring will fit most 11-15 comfortably.
Adjustable Gold Band Mood Ring Color Changing Jewelry listed in: