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 World of Colored Gems

By Gleim the Jeweler

The jeweler allows me to wear the sapphire blue lake on my finger, emerald green leaves around my neck, and take the citrine sunset with me wherever I go. Jewelry has become my daytime link to nature in an office with no windows. And if I have to work late, there’s nothing like diamond stars and a pearl full moon against an onyx night sky.

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“Gossip” emerald cut three stone rings by Goshwara.

This wonderful quotation, by author Astrid Alauda, perfectly expresses the emotional connection that has been provided by colored gemstones for thousands of years.

Fine colored gemstones have been revered throughout history. Gemstones have been imbued with the power to foretell events, strengthen memory, quicken intelligence, ensure purity, avert lightning, prevent intoxication, ensure happiness and are often equated to the fountain of youth.

What Defines a Colored Gemstone?

Colored gemstones are described as all the various gemstones except for diamonds. Only a select few of the vast number of minerals known qualify as gemstones. In order to become a gemstone, the mineral must be rare and beautiful and be durable enough to be worn as jewelry.

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Blue sapphire ring by AG Gems.

Precious vs. Semi-Precious Gems?

In the past, the term “precious” was used to describe diamond, emerald, ruby, and sapphire. The term “semi-precious” referred to all other gemstones. Today, most jewelers and gemologists agree that these terms no longer accurately reflect the true value of these gems. In particular, some species of colored gems, such as alexandrite or demantoid garnet, are so rare that they have been known to command prices exceeding those of emerald, ruby, and even diamonds.

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Alexandrite and diamond pendant by Omi Privé.

Gemstones generally can be grouped into three major clarity categories:

  1. Gems that are flawless or have very minor inclusions (e.g. aquamarines and amethysts)
  2. Gems that are moderately included (e.g. rubies and sapphires)
  3. Gems that tend to be highly included (e.g. emeralds and red tourmalines)

Color is the single most important deciding factor in determining the value of a gemstone, followed by the cut. The cut of a gemstone is designed to bring out the best possible color or colors in the rough uncut material while retaining as much weight as possible. The color in a fine gem is saturated evenly throughout the stone and is of a brilliant deep, rich, and pleasing color—not too dark and not too light.

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Indicolite earrings by Erica Courtney.

Each variety of colored gemstone has a range of highly prized colors that have evolved over the years. Many of these colors are tied to historical sources such as “Burmese” rubies from Burma, “Kashmir” sapphires from India, and “Persian” turquoise. This is by no means a sure bet. Not all rubies from Burma have the “Burmese” signature color and furthermore, you may find a fine color from a ruby that was mined in Thailand.

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Cushion cut Mozambican Ruby ring by Real Gems Inc.

Ultimately the wearer decides what color speaks to them, keeping in mind that this may not be that color defined as being the most valuable. Since we all perceive color differently it’s ultimately a very personal choice.

Today, with the ever-increasing advances in gemstone enhancements and synthetic gemstone production, it is more important than ever to work with a reputable and properly trained jeweler.

About Gleim the Jeweler

We have been serving the Peninsula since 1931 and have been members of the American Gem Society (AGS) since 1954. Our membership with the AGS assures you that we earn and maintain the education necessary to provide you with the most up to date information about gems and their different markets.

We also have American Gem Society Accredited Gem Laboratories, assuring you that we have the proper instruments to identify and grade gems. And, what’s perhaps most important, we love colored gems!

Five Trends to Look for at the 2017 Oscars

If you haven’t already, be sure to mark your calendar for this Sunday, February 26, so you don’t miss the 89th Academy Awards! Millions of film and fashion fans will be tuning into ABC at 7:00 p.m. EST/4:00 p.m. PST when the stars begin to walk the red carpet.

What will this year’s fab fashions be? Here’s a list of five trends that are predicted to be “scene” on the stars. We’ve included a few designs from AGS members that we think would best complement these lovely looks.

Flowers and Nature

Floral designs never seem to go out of style and with spring just around the corner, what better place to display some flower power than at the Oscars! They can either be classic and demure or big, bold, and bright! With the growing trend of floral patterns, other nods to nature are sure to follow. Animals, birds, and leafy plants are leaving a trail on this season’s designs.

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Sapphire, white and brown diamonds flower ring by Supreme Jewelry.

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Flexible diamond tiger cuff
by Roberto Coin.

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Cobra drop earrings with diamonds
by John Hardy.

Pink

Here’s a hue that has been popular of late. When it comes to pink gemstones, we can choose from pink diamonds, pink sapphire, Morganite, kunzite, and rose quartz, to name a few! Which gal—or guy—will be thinking pink on the red carpet?

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Fancy light purplish pink heart shape diamond necklace by Scott West Diamonds.

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Fancy pink diamond ring by
Jeffrey Daniels Unique Designs.

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Pink sapphire flower cluster diamond earrings and pendant by Whiteflash.

One Shoulder

The elegant drape of a one-shoulder dress or top embodies a mix of sophistication and sultriness. An ensemble like this should be punctuated by some serious sparkle!

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Diamond Angel Feather ring
by KC Designs.

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The Helen necklace by Harry Kotlar.

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White Kites Bird long earrings
by HOF X Stephen Webster.

Satin

Reminiscent of old Hollywood, satin is one of the biggest trends this spring. Expect to see the silky-smooth and shimmering fabric in bright jewel tones. Enhance the look with gorgeous jewels like these!

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Trillion cut Tanzanite and diamond earrings
by AG Gems.

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A two-tone gold necklace featuring rose-cut emeralds and diamonds by Yael Designs.

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Paraiba tourmaline and diamond ring by Takat.

Color Blocks

Gone are the days of drab black and gray. Enter the brilliant and daring blocks of color! Bold and beautiful gemstones make these jewelry designs absolute showstoppers.

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“Amazon” pendant featuring peridot accented by purple garnet and diamonds by Erica Courtney.

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“Gossip” emerald cut citrine earrings with diamonds by Goshwara.

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Rhodolite and spessartite garnet ring
by Omi Prive.

Shopping for fine jewelry should be just as exciting as the Oscars but without unwelcome surprises. American Gem Society (AGS) credentialed jewelers adhere to standards that not only comply with governing laws, but that go beyond, to ensure that you are buying from jewelers who have the knowledge and skill to help you make the most informed buying decision. To find an AGS jeweler near you, click here, and leave the nail-biting uncertainty for the Oscars!

‘Tis the Season for Stackables, Studs, and Solitaires

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The holidays are only a few days away, so if you’re still looking for something super special for the season, the American Gem Society (AGS) suggests stackables, studs, or solitaires. These pieces are always on trend and are regular go-to items in any fine jewelry wardrobe.

Below are some dazzling designs by our AGS members that are sure to inspire. If you need more ideas, you can always count on an AGS jeweler to help. Every year, our AGS members are required to continue their gemological education, staying up-to-date on changes and trends in the jewelry industry. Search for an AGS jeweler near you by clicking here.

Stackables

The beauty of a stackable bracelet or ring is that you can wear them individually, mix and match to change the look or wear them all together. So many options!

Studs

These days, when it comes to studs, the possibilities are endless! You could sport a solitaire diamond or gemstone by day, and then dress it up with an earring jacket by night.

Solitaires

Often a solitaire is presumed to be a round diamond, simply set as a ring or pendant. But today you’ll find these singular stones come in all shapes, sizes, and species—like corundum (ruby and sapphire) and quartz (amethyst and citrine).

Always keep in mind, when purchasing a diamond—whether it’s a loose stone or mounted—to ask your jeweler for an AGS Laboratories Diamond Grading Report. That way you can be confident that your diamond has been consistently and accurately graded by the only nonprofit diamond grading laboratory with the mission of consumer protection. Accept no substitutes. Happy shopping!

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.

Election Day Sparkle

It’s election day in the USA! Months of election coverage culminates as America heads to the polls. We wanted to pay tribute to this important occasion in our own way: with red, white and blue jewelry designs from members of the American Gem Society (AGS). These beautiful pieces get our vote!

Red

Let’s begin with some bright and cheery red gemstones. Rubies naturally come to mind, but when it comes to red hues—there are many varieties of gemstones to choose from.

Jeffrey Daniels Unique Designs

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A triangular rubellite set in 18k hammered gold, framed by bead set diamonds.


Supreme Jewelry

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A red garnet pendant set in 18k rose gold framed by white diamonds.

United Color Gems

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Oval shaped red spinel earrings set in 18k white gold with white diamonds.

White

The color white has long stood for innocence, purity…and a color you’re not supposed to wear after Labor Day. But we all know diamonds and pearls can be worn any season!

Spark Creations

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These diamond earring jackets will give a simple diamond stud a little more oomph.

Honora

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The perfect balance between modern and feminine. White freshwater cultured pearls and sterling silver bracelet.

Caro 74

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Floral diamond pendant with a diamond bale, set in 14k white gold.

Blue

We can thank Mother Nature for some truly beautiful, truly blue gemstones! Be true blue with these wonderful designs!

Armadani

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Star sapphire cabochon halo ring with round brilliant diamonds.

Carelle

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Tanzanite Round Stack earrings in 18k yellow gold.

JB Star

A Passion for Precision.. A Labor of Love

Platinum pendant featuring a round diamond center encircled with perfectly matched round sapphires and pave accents.

No matter how you vote, when you choose to shop with a trusted AGS jeweler, you’re voting for a winner! Click here to search for an AGS jeweler near you.