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!

Corundum of Many Colors: Sapphire

As we turn our calendars to September, we start thinking of things like heading back to school, sipping on a pumpkin spice latte, and planning our fall fashions. For those celebrating a birthday in September, they’re thinking of their birthstone: sapphire!

Although sapphire typically refers to the rich blue gemstone variety of the mineral corundum, this royal gem actually occurs in a rainbow of hues. Sapphires come in every color except red, which would then be classified as ruby.

Trace elements like iron, titanium, chromium, copper, and magnesium give naturally colorless corundum a tint of blue, yellow, purple, orange or green, respectively. Sapphires in any color but blue are called “fancies.”

Pink sapphires, in particular, tow a fine line between ruby and sapphire. In the U.S., these gems must meet a minimum color saturation to be considered rubies. Pinkish orange sapphires called padparadscha (from the Sri Lankan word for “lotus flower”) can actually draw higher prices than some blue sapphires.

Due to the remarkable hardness of sapphires—which measure 9 on the Mohs scale, second only to diamond—they aren’t just valuable in jewelry, but also in industrial applications including scientific instruments, high-durability windows, watches, and electronics.

Sapphires make stunning gifts for anyone born in September or celebrating a 5th or 45th wedding anniversary, so be sure to visit an AGS jeweler. They will help you find that perfect gift, whether you’re seeking the classic blue or another shade from the sapphire rainbow.

Need some inspiration? View this collection of designs featuring the sapphire!

5 Pieces of Jewelry to Take on Your Summer Vacation

By Robin Skibicki

“Summer, summer, summertime / Time to sit back and unwind.” – DJ Jazzy Jeff & The Fresh Prince, Summertime

As thoughts of summer vacation drift through our heads, so does the ultimate question: “What am I going to pack?!” Whether you’re traveling overseas, across states—or even planning a staycation—it’s good to have a plan.

Although we’d love to help you pick out your various outfits and toiletries—they aren’t our area of expertise. But we CAN give you some great ideas on what jewelry to bring with you.

It’s often a challenge deciding which items of jewelry to take, depending on the outfits you pick. But it’s important to note that it’s best to leave the most valuable and delicate pieces at home. Before you pack, we have this recommended read from Jewelers Mutual Insurance Group: The Pocket Guide to Traveling with Jewelry.

Yet, no outfit is complete without the punctuation of fine jewelry. Here are five pieces from a few of our AGS members that would make great travel companions! Click on the images below to get a closer look.

“Caprice” multiway diamond eclipse earrings, by Mastoloni.
When you can bring one pair of earrings and wear them three different ways, you’re covered! Wear as a dangle, as a diamond and pearl stud, or wear the pearl by itself.

 

Wide diamond band from Gabriel & Co. “Lusso” collection.
A diamond band with alternating 14k yellow and white gold gives the illusion of wearing multiple rings. Easy peasy!


Gabriel-14k-Yellow-And-White-Gold-Lusso-Wide-Band-Ladies-Ring_LR50892M45JJ-3

 

Two-piece convertible diamond heart pendant, by Lisa Bridge, Ben Bridge Jeweler.
This romantic pendant is convertible and can be worn three ways: with both diamond pavé and heart pieces together, or either the center circle or heart frame separately.

 

Rainbow sapphire butterfly brooch, by Dilamani.
A brooch you say? You bet! Dress up any top, scarf, hat—or even a hairstyle—with a brooch. A brooch can also be turned into a pendant with the addition of a chain. So many style options!

 

Custom reversible classic chain bracelet, by John Hardy.
Here’s another “gem” we found: one bracelet with two looks! John Hardy gives you the opportunity to customize your own chain bracelet with any gemstone look. Below is the combo we designed. The 18k bonded gold side sparkles with diamond pavé. The sterling silver side has a pop of color with amethyst. Which look would you create for yourself?

 

Visit an American Gem Society jeweler near you for more helpful hints on what to bring—and what not to bring—on your summer vacation. Happy travels!

Bring on Spring: Be Inspired by the Colors of the Season

“April hath put a spirit of youth in everything.” – William Shakespeare

Now that spring has arrived, we look forward to the signs of renewal. From fastidiously cleaning our homes and joyously changing out our wardrobe to reconnecting with family and friends for a spring holiday or wedding. It’s easy to love this time of year!

Even our jewelry is complementing the seasonal spectrums, with soft pastels and bright, happy colors. Here are some spring-inspired styles from a few of our American Gem Society (AGS) members.

 

We’ve all got that extra spring in our step thanks to the warmer weather and the chance to don the colors of the season in our homes, wardrobe, and fine jewelry! Search for an AGS-credentialed jeweler near you and they’ll help you find the perfect piece for any springtime occasion.