Six Displays of Optical Phenomena in Gemstones

By Robin Skibicki

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! In this article, we’ll discuss six of the most familiar (and magical) displays of optical phenomena in gemstones.

Adularescence

Adularescence is the phenomena 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.

 

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.

 

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.

 

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!

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.

 

Are you ready to see some of these displays in person? Visit a credentialed AGS jeweler near you and ask to see some gemstones that exhibit optical phenomena!

The AGS Suppliers’ Reception and Showcase

Each year during the American Gem Society’s (AGS) annual conference, Conclave, we feature an exclusive event called the AGS Suppliers’ Reception and Showcase. This special evening gives our supplier members the opportunity to showcase their incredible jewelry to their fellow AGS members, the AGS retailers.

What makes this event so special is when we do a showcase…we do it up right! This year, with the generous sponsorship of the bridal magazine, The Knot, our showcase featured 23 AGS members whose most gorgeous and luxurious jewelry was worn by models in wedding gowns.

This showcase is not open to the public, but we’d like to give you a special peek into the fashions and festivities that took place this year!

This showcase is not open to the public, but we’d like to give you a special peek into the fashions and festivities that took place this year!

Stay tuned for more images featuring our AGS members.

Visit an AGS-certified jeweler near you and ask them to show you some of their favorite designs. And if you have a special design in mind, do not hesitate to ask—they’ll be happy to find it for you or bring your idea to life!

6 Jewelry Trends for 2017

By Jennifer Heebner

Directional colors and styles of jewelry shape up annually based on a trio of familiar factors—what’s trending in Hollywood, what the fashion designers are sending down the runways, and the gem material that Mother Nature provides. The following six jewelry trends were born from the intersection of these occasions, so keep them top of mind this year for gifts and self-rewards.

Oversize earrings. Calderesque versions in costume materials were evident on models at several spring couture shows though karat-gold numbers are an heirloom-quality choice. AGS members have plenty of options!

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Chandelier earrings in 18k gold with rose-cut diamonds and rubies from Vivaan.

 

Hearts. Love takes a literal interpretation next season. Just look at the word itself on sweaters by Michael Kors! While hearts can elicit mixed reactions—are they kitsch or cool?—know the fashion gods have committed to them this year. Would you wear a heart? Diamond options (here and below) are hard to resist!

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Ring in platinum with a heart-shaped yellow diamond, a heart-shaped emerald, and colorless diamonds from Setaré.

 

Choker necklaces. These continue to enjoy the spotlight. Both Céline and Versace sent choker-wearing models down the spring runways to create chic style messages. Chokers can feature traditional (think cameos) or contemporary elements ideal for wear dressed up for evening or down with denim during the day.

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Choker necklace in 18k Strawberry Gold with Chocolate and Vanilla diamonds and a Neon Paraiba Tourmaline from Le Vian.

 

Mismatched earrings. These range from subtly mismatched styles—one stud and one drop—at Dior to completely different designs on each ear. And related to this trend of uneven mates are the large single earrings being worn solo. No matter how you wear the mismatched look, its novelty will attract attention and admirers.

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Mismatched earrings in 18k gold with diamonds from Erica Courtney.

 

Statement necklaces. Recent red carpet jewelry placements have fueled a growing appetite for attention-grabbing necklaces. Expect to keep seeing bibs, big pendants on long chains (think Givenchy’s über-cool agates), and multi-layer options that build a look by using many slimmer styles.

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Collar necklace in 18k gold with blue chalcedony from Goshwara.

 

Pearls. From natural-color Chinese freshwaters to Japanese Akoya and South Sea varieties, pearls are making a comeback among jewelry designers for their iconic beauty. Even fashion brands like Gucci worked pearl accents into 2017 lines, further cementing the lustrous orb’s must-have status.

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Earrings in 24k gold with baroque-shape freshwater pearls and diamonds from Lika Behar Collection.

If you’re loving these trends, search for an AGS jeweler near you. They’ll help you find any of the above designs, match you with similar looks, or help you design your very own trend-setting style!

Four Fun Facts About January’s Gemstone

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Rhodolite garnet and emerald sunbeam earrings by Ricardo Basta Fine Jewelry.

If you’re celebrating a birthday or any special occasion this month, then the garnet is a worthy addition to your fine jewelry wardrobe. Here are four fun facts about the colorific January gem:

1. Not all garnets are red.

Garnet is actually the name of a group of minerals that comes in a rainbow of colors, from the deep red of the Pyrope garnet to the vibrant green of Tsavorites. Some rare garnets are even blue, colorless, or—most rare of all—change colors in different lights. But the most common color is a beautiful range of reds, from rust colored to deep violet-red.

2. It’s more than just a gemstone.

For thousands of years, the garnet has lived a glamorous life as a gemstone. But in the past 150 years, it has also been put to the test as an effective industrial mineral. In the United States, garnet has been utilized for waterjet cutting, abrasive blasting, and filtration.

3. Their inclusions make them unique.

Some garnets have inclusions that are part of the beauty of the overall stone (like “horsetails” in Demantoid garnets, or Hessonite garnets which sometimes have a “turbulent” look). So you may discover that you like the distinctive look these inclusions bring to the piece.

4. Garnets have been around for a very long time.

The garnet is so durable, remnants of garnet jewelry can be found as far back as the Bronze Age. Other references go back to 3100 BC when the Egyptians used garnet as inlays in their jewelry and carvings. The Egyptians even said it was the symbol of life. The garnet was very popular with the Romans in the 3rd and 4th Century.

Today, the garnet can be found in a range of jewelry pieces and styles, from beautiful rings to stunning tiaras. Since the garnet can come in a range of colors, rare garnets in green or blue make breathtaking pieces, especially in pendants or drop earrings.

Here are a few designs from AGS members featuring the many colors of the garnet. Click on the images for a larger view.

To learn more about the wide range of garnet color options and to pick the perfect piece, search for an AGS jeweler near you!

The Five Trends of Christmas

If you’re in search of some great gift ideas—or some hints to give your true love—then look no further than today’s hottest jewelry trends. Below we feature designs by AGS members that represent these styles, just in time for Christmas.

Hoop Earrings

The hoop is a wonderful go-to classic that works for both day and night. They can be subtle silver or gilded gold loops, be studded with diamonds and gemstones, thread through the ear from behind vs. the front, or lay close to the lobe for the “huggie” style.

 

Pearls

You can never go wrong with pearls—they are forever chic, sophisticated, and classy. They can be mixed with metals and other gemstones, and worn with anything from evening gowns to jeans.

 

 

The Y-Necklace

Like the lariat, the Y-necklace doesn’t need to be wrapped or knotted. They are elegant all on their own, adding a slick touch of glamour to the neckline.

 

Slices

If you would love to have gemstones at an accessible price, slices are a wonderful alternative. Designers have discovered that slices also reveal the unique patterns and inclusions in the gemstone, enhancing their raw beauty.

 

 

Rainbow

It’s hard not to be happy when you see the vibrant colors of a rainbow. The gemstones can be placed together in a single piece or stacked with gemstone bands and bracelets. No matter the combination, they make a great addition to your jewelry wardrobe.

 

These trends only scratch the surface of what’s new and en vogue. If you are looking for some more ideas, be sure to ask your trusted jeweler. AGS jewelers keep up-to-date with the latest trends in the industry and are always happy to help you choose the best look for you and your loved ones. To find an AGS jeweler near you, click here.

Chase Away the Winter Blues With December’s Birthstones

decemberbluesDecember’s birthstones offer three ways to fight the winter blues: tanzanite, zircon, and turquoise—all of them, appropriately, best known for beautiful shades of blue.

These gems range from the oldest on earth (zircon) to one of the first mined and used in jewelry (turquoise), to one of the most recently discovered (tanzanite).

Below is a collection of beautiful blues designed by our AGS members. Click on the images to see all the beautiful details!

Tanzanite

Tanzanite is the exquisite blue variety of the mineral zoisite that is only found in one part of the world. Named for its limited geographic origin in Tanzania, tanzanite has quickly risen to popularity since its relatively recent discovery.

Due to pleochroism, tanzanite can display different colors when viewed from different angles. Stones must be cut properly to highlight the more attractive blue and violet hues and deemphasize the undesirable brown tones.

The majority of tanzanite on the market today is heat treated to minimize the brown colors found naturally and to enhance the blue shades that can rival sapphire. Between its deep blue color and its limited supply, tanzanite is treasured by many—whether one is born in December or not!

 

Zircon

Zircon is an underrated gem that’s often confused with synthetic cubic zirconia due to similar names and shared use as diamond simulants. Few people realize that zircon is a spectacular natural gem available in a variety of colors.

Zircon commonly occurs brownish red, which can be popular for its earth tones. However, most gem-quality stones are heat treated until colorless, gold or blue (the most popular color). Blue zircon, in particular, is the alternative birthstone for December.

Whether you’re buying blue zircon to celebrate a December birthday, or selecting another shade just to own a gorgeous piece of earth’s oldest history, zircon offers many options.

Turquoise

Turquoise, the traditional birthstone of December, is also gifted on the 11th wedding anniversary. But buying turquoise doesn’t require special occasions; its namesake blue color has been internationally revered for centuries as a symbol of protection, friendship, and happiness.

Thanks to its historical and cultural significance in many Native American tribes, turquoise remains most popular throughout the southwestern U.S.—which supplies most of the world’s turquoise today.

Turquoise is one of few gems not judged by the 4Cs of diamond quality. Instead, the main factors that determine its value are color, matrix, hardness, and size. The most prized turquoise color is a bright, even sky blue. Greenish tones can lower the value of a stone, although some designers prefer it.

Because of its fragility, turquoise is often treated to enhance durability and color. Some treatments involving wax and oil are relatively harmless, while other methods—including dye, impregnation, and reconstitution—are more controversial. Seek out an AGS jeweler who can help you find the best quality turquoise.

 

Shopping for fine jewelry should never make you blue! Make sure you shop with a trusted jeweler and buy it with confidence. Click here to search for an AGS jeweler near you.

October’s Birthstones are Bursting with Color

octoberbirthstonesOctober features two incredible birthstones: opal and tourmaline. They each display an exciting and intense array of colors, making them popular choices for jewelry designers and collectors.

Opal

The name “opal” derives from the Greek Opallos, meaning “to see a change (of color).” They range in color from milky white to black with flashes of yellow, orange, green, red, and blue. An opal’s beauty is the product of contrast between its color play and its background.

Opal is a formation of non-crystalline silica gel that seeped into crevices in the sedimentary strata. Through time and nature’s heating and molding processes, the gel hardened into the form of opals. The opal is composed of particles closely packed in spherical arrangements. When packed together in a regular pattern, a three-dimensional array of spaces is created that gives opal its radiance.

Approximately 90 percent of the world’s precious opal comes from Australia. The following are other countries that produce precious or fancy varieties: Brazil, Mexico, United States, Hungary, Peru, Indonesia, Honduras, Guatemala, Nicaragua, Slovakia, Czech Republic, and Ethiopia.

Like fingerprints, each opal is totally unique! To get a really good look at the opals in these designs, click on the images below for a larger view.

Lightning Ridge Collection

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Blue-green black opal accented by fine white princess cut diamonds and round brilliant cut diamonds.

 

Lika Behar Collection

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Sterling silver and 24k gold “Ocean” necklace, featuring a one-of-a-kind boulder opal framed by diamonds.

 

Parlé

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Australian black opal and diamond earrings set in 18k yellow gold.

 

Yael Designs

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An 18k rose gold bracelet featuring rose cut fire opals and brilliant cut white round diamonds.

 

Tourmaline

Since tourmaline is available in a wide variety of colors, it is ideally suited to almost anyone’s taste. It is known for displaying several colors in the same gemstone. These bi-color or tri-color gems are formed in many combinations; the gemstones with clear color distinctions are highly prized.

One multi-color variety is known as watermelon tourmaline and features green, pink, and white colors bands. To resemble its namesake, the gemstone is cut into thin slices having a pink center, white ring, and green edge.

Tourmaline is found in many localities including Brazil, Afghanistan, East Africa, and the USA.

The following designs feature the varying hues of tourmaline. Click on the images to see a larger view.

 

Erica Courtney

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“Rain Drop” 18k yellow gold studs featuring
Paraíba tourmaline accented with diamonds.

 

Supreme Jewelry

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This unique ring displays a butterfly fluttering around petals of  sliced tourmaline, framed by diamonds.

 

Omi Privé

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A cushion cut pink tourmaline and diamonds are set in platinum and 18k rose gold.

 

Crevoshay

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“California Dreaming” is an 18k gold pendant artfully displaying the many colors and varieties of tourmaline.

On behalf of everyone at AGS, we send our best wishes to those celebrating a birthday or anniversary in the month of October!

If you are shopping for opal or tourmaline jewelry, search for an AGS credentialed jeweler near you: www.americangemsociety.org/en/find-a-jeweler.