Fascinating Phenomena in Gemstones

There are several varieties of gemstones that display optical phenomena, which describes the many ways light interacts with the structural features or inclusions (internal characteristics) in the gemstone. Often these gemstones will be fashioned in a particular way that best displays these effects.

The science of optical phenomena can be fascinating, although the mystery and allure of these effects are what initially attract us! Below are six of the most familiar (and magical) displays of optical phenomena in gemstones.

Play-of-Color

Play-of-color is created by a combination of diffraction and interference, and is the result of the microstructure of opal: the chameleon of a thousand colors and October’s birthstone!

Opals are made up of many layers of small, stacked spheres of silica. These spheres diffract light, splitting it into a spectrum of colors. The layers of these spheres create interference allowing certain colors to dominate, depending on the angle the opal is viewed.

Asterism

Asterism, or stars, relates to the four- or six-rayed star pattern of light produced by the fibrous inclusions, elongated needles, or growth tubes in a gemstone. This singular, celestial-like phenomenon is best seen in a gemstone cut en cabochon.

 

Chatoyancy

Chatoyancy [sha-TOY-an-cee] is also known as “cat’s eye.” Fine needle-like or fibrous inclusions within the gemstone are what causes this effect. Again, stones fashioned as cabochons display this effect the best.

 

Color Change

A small number of gemstones display the color change optical phenomena. Depending on the lighting environment, the color change appearance can vary due to the shifting wavelengths. The technical term for this is photochromism or photochroism; “color-change” is a lot easier to say!

The best-known color changing gemstone is alexandrite. When viewed in sunlight, it appears greenish. When placed under incandescent light, it appears reddish. Other varieties of color-changing gemstones include sapphire, garnet, spinel, diaspore, and tourmaline.

 

Adularescence

Adularescence is the phenomenon typically seen in moonstone, which is a member of the feldspar family. It produces a billowy soft blue to milky white light that appears to move across the gemstone. This occurs when light hits the alternating layers of albite and orthoclase, which are two differing forms of feldspar within the gem.

The layers of feldspar interfere with the light rays causing them to scatter and the eye to observe adularescence. The effect is best seen when the gemstone is cut en cabochon [en CAB-ah-shawn]—that is, with a polished, domed top and a flat or slightly rounded base.

 

Labradorescence

Labradorscence [lab-ra-dor-es-cence] is an optical characteristic often seen in labradorite. The effect is a spectacular play-of-color that is metallic or iridescent, displaying blue, green, red, orange, and yellow. This is an interference effect within the gemstone caused by internal structures that selectively reflect only certain colors.

 

Are you ready to see some of these displays in person? Visit an American Gem Society (AGS) jeweler near you and ask to see some gemstones that exhibit optical phenomena!

Living Coral: Pantone’s 2019 Color of the Year

By Isabelle Corvin, CG, Staff Gemologist at Panowicz Jewelers.

pantone-livingcoralPantone has officially announced it’s 2019 Color of the Year as “Living Coral” (16-1546)!

This bold, energetic, and dynamic color is sure to liven things up for the New Year! Pantone calls Living Coral “sociable and spirited” and says that it is a nurturing color. It’s a blended hue of orange and pink, creating a bright spot in our everyday lives.

The first known written use of the word “coral” to describe a color was in 1513, and the use of “coral pink” was in 1892. The term “coral” for color has been used to described reds, oranges, and pinks, as well as mixed colors from those components.

Cheerful and shocking, coral lends itself well to all aspects of décor, graphic design, and fashion. In fact, you’ll find several gemstones that display this bright, bold, and beautiful color!

Padparadscha sapphire and Rhodochrosite match Living Coral almost perfectly, with their lively blend of just the right amount of pink and orange.

 

Padparadscha is a high-energy stone with an exotic look. The name comes from the Sanskrit word for “lotus.” And indeed, some lotus blossoms exhibit Living Coral excellently!

Rhodochrosite embodies the feeling of Living Coral with its color and the belief that it is a powerful stone for opening your heart once more. It is said to heal emotional wounds and be a guide for finding love.

Other gemstones that depict shades of Living Coral are additional sapphire colors, and some hues of topaz and spinel, as well as certain garnets.

 

Living Coral reminds us that the world around us is alive, filled with wonder and magic, if we only take a few moments to look. The color dives deep into our hearts, beckoning an appreciation for life’s moments and worthwhile memories.

According to Pantone, they chose this color for that very reason. In a world so immersed in technology, we all seek connections. Living Coral is a delight to the eyes and a light to the heart.

Happy New Year!

Jewelry images by credentialed AGS members. Visit ags.org/findajeweler to find an AGS jeweler near you.

isabelle

Isabelle Corvin is an AGS Certified Gemologist (CG) who is the Staff Gemologist at Panowicz Jewelers. Since she was 14-years-old, she knew she wanted to be a gemologist. Ms. Corvin also writes for Panowicz Jewelers’ blog.