A new generation of dynamic color changing jewelry is providing a fresh take on that much-maligned artisan fair staple: the mood ring. The accessory’s original iteration debuted in the 1970s and centered on quartz-encased thermotropic liquid crystals, which faded from black to green to pale blue when exposed to the body’s fluctuating temperatures.
Today, fresh design concepts for color-changing jewelry have emerged. Alexandrite as well as ultra-rare types of diamonds and sapphires react when exposed to different lighting conditions. And when they are positioned as the central stone in a ring, the effect is—to use a term from the mood ring’s birth decade—out of sight.
Here we break down the three color-changing gems you ought to keep your eye on.
Chameleon Diamonds

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Color changing diamonds, or Chameleon diamonds, are among the rarest and on earth. And they remain (mostly) a mystery— the GIA describes them as being “so rare and valuable, researchers have found it difficult to procure samples to study.” Under normal conditions, Chameleon diamonds are a yellowish green hue (see the image on the right), but when heated up to 302° Fahrenheit or exposed to light after being stored in the dark, the Chameleon quickly darkens into an orange-yellow (see ring on the left). The change doesn’t last long, but the effect is mesmerizing. Few examples of Chameleon diamonds have ever come up for auction, but when they do they make a splash—back in 2011, Christie’s sold an 8.8-carat chameleon diamond ring in Hong Kong for $590,000, or $67,000 per carat.
(Image above: Les Chameleon, a ring with a 1.13-carat color changing Chameleon green diamond accented with Argyle Pink diamonds. $44,000; available through Argyle Pink Diamonds Select Ateliers.)
Alexandrite

In bright daylight, the highly collectible alexandrite—first unearthed in Russia in the early 1800s and named in honor of Russian czar Alexandar Nicholavich—is typically a greenish blue or dark green. But in lower light the gem warms into a pinkish red, as shown in this 1.41-carat alexandrite ring from M.S. Rau Antiques.
(Image above: An alexandrite surrounded by round brilliant white diamonds, all set in 18-karat white gold. $28,500; available at M.S. Rau Antiques.)
Sapphires

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Color changing sapphires are quite rare as well—the most well-known variations fade from blue to violet or from purple to red under different lighting, but there are more. Like this 17.6-carat example, which transforms from a deep ocean-like blue to a dark turquoise when brought into lower light.
(Image above: Color changing sapphire accented by 3.64 carats of white diamonds, mounted in platinum. $198,500; available at M.S. Rau Antiques.)