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!

Jewelry Trend Watch: East-West Settings

If you’re looking for a style that takes traditional in a different direction, check out the east-west setting. It’s the lastest jewelry trend that places the gemstone horizontally vs. the classic vertical setting. Whether the cut is oval, pear, marquise, or emerald, the east-west setting will be noticed!

We’re spotlighting a few designs from our AGS members that feature this eye-catching setting. Click on the images to get a closer look.

 

 

Looking to see some east-west set jewelry in person, visit an American Gem Society credentialed jeweler near you: www.ags.org/findajeweler.

The Beauty of a Brown Diamond

Did you know that brown diamonds show more flashes of colored light than “colorless” diamonds?

If you are in the market for brown diamonds, be sure to ask your jeweler for an AGS Laboratories Colored Diamond Document. It’s a grading report that presents the technical aspects and nuances of colored diamond grading to jewelry buyers with easy-to-understand verbiage and graphics.

Brown diamonds will no longer be described simply as “a brown diamond,” but will be communicated visually, highlighting the nuances within the diamond’s color. For example, a diamond with even distribution of brown throughout and hints of orange, could be described as a deep, rich, brown diamond with moderate orange accents.

Click the image below to view the Colored Diamond Document.

AGSL-CDD

“Brown diamonds are beautiful and are an alternative choice to the more traditional colorless diamonds. They are also trending as an affordable choice for fine jewelry,” said Jason Quick, Laboratory Director at AGS Laboratories. “We recognized a growing need in the market and decided to create a tool that will truly enhance consumers’ buying experience.”

AGS Laboratories encourages jewelry buyers who are shopping for diamonds to always ask for a diamond grading report from an independent third-party laboratory so that they can better understand the quality of the diamond they are buying. To find an American Gem Society retailer, visit americangemsociety.org/findajeweler.

To learn more about AGS Laboratories Colored Diamond Document, visit agslab.com/browndiamonds.

Here are a few designs we love from members of the American Gem Society that feature brown diamonds.

Spinel: The Coolest Gem You’ve (Probably) Never Heard Of

By Isabelle Corvin, CG, Staff Gemologist at Panowicz Jewelers

Three Spinel Crystals

Red Spinel

Spinel is an oxide mineral that crystallizes in the cubic structure and has quite the mixed-up history.

As of 2016, it is also the newest birthstone to be added to the birthstone list! August babies now have a choice between vivid peridot and alluring spinel.

The word “spinel” comes from the Latin word Spinella, which means “little thorn” or “arrow-shaped.” Spinel gems come in a wide range of colors and saturations, though perhaps the most famous (and mistakenly infamous) is the red variety.

In ancient cultures, red spinel was always grouped together with rubies, and sometimes garnets, since the rough (and even polished and cut) crystals look so similar. In the modern age, the gems can be separated, but much of spinel’s history is tied up in the lore of rubies.

Red spinel ring, by Omi Privé.

Spinel-Omi

The oldest known spinel dates back to 100 B.C. and was found in Kabul, Afghanistan, inside a Buddhist temple. Red and blue spinels were also being used in crafting by the Romans.

The most famous spinel is also the most famous example of mistaken identity in all of gemological history. A “ruby” known as the Black Prince’s Ruby is our culprit. It is a red gem set in the Imperial State Crown of the British crown jewels. The gemstone is uncut, but polished, and weighs approximately 170 carats. The gem has never been removed from its original setting, so the weight is only estimated.

This amazing gemstone, however, is no ruby. It is, in fact, a spinel.

The Imperial State Crown. Image courtesy of GIA.

QueensCrown-lrg

The Black Prince was the son of Edward III, and reportedly received the gem from Don Pedro the Cruel, King of Castille as a reward. Legend has it that the spinel was one of the gems worn by Henry V on his helmet and that it deflected a fatal blow, saving his life during the Battle of Agincourt.

Whether true or not, the gem was thought to be ruby for many years, until technology and the knowledge of gems improved enough to separate gems on more than mere color.

This royal stone is not the only spinel in disguise. Empress Catherine II of Russia had a crown that bore an estimated 400-carat spinel. Likewise, Queen Victoria had a very dark red spinel called the Timur Ruby.

It doesn’t help matters when spinel and ruby often form together in the earth! In 1783, mineralogist Jean Baptiste Louis Rome de Lisle finally separated spinel from ruby, realizing that the two minerals were completely different.

Further confusion arises with spinel’s true nature even now.

Many pieces of inexpensive birthstone jewelry have an imitation of the true birthstone: something that looks like—but isn’t—the real thing. The majority of these are made with synthetic spinel, grown in a laboratory rather than the ground, but boasting the same chemical make-up.

The natural gem is lovely, but many only know of its synthetic counterparts.

Each color of spinel is thought to provide different benefits to the wearer, from protection to enhancing creativity and kindness, to better cognitive abilities. Colorless spinel is rare, and no current mines exist that produce it.

Spinel earrings set in 18k rose gold, by AG Gems.

Spinel-AGGems (2)

The most common colors seen in jewelry are red and blue, with the hues ranging from highly saturated to perfectly pastel.

Other popular colors are yellows, purples, and pinks, although the gem comes in every color. Black spinel is found in many pieces, and once again, is often confused for other black gems like hematite, black diamond, and black onyx.

Black spinel and white sapphire pendant, by Dilamani.

Spinel-Dilamani

Spinel is mined in many locations, including Madagascar, Sri Lanka, Myanmar (formerly Bruma) Brazil, Sweden, Pakistan, and Russia, among others. It can even be found in the USA.

Additionally, small crystals have been found on meteorites, a trait spinel shares with the other August birthstone, peridot.

For a gemstone many have never heard of, it might be the most famous of all. It is the hidden star of the show, silently shining on as the world ignores it or mistakes it for another stone altogether.

Pink spinel and diamond drop earrings, by JB Star.

Spinel-JBstar

But spinel is worth a first, and second, glance. With spectacular colors, excellent durability and an amusing history, it’s the perfect addition to anyone’s gem and jewelry collection.

Spinel truly deserves the title: The Coolest Gem You’ve (Probably) Never Heard Of!

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.

This is not a brown diamond

By Donna Jolly, RJ

You may think this big, beautiful diamond in the ring below is a brown diamond. It is, but it’s so much more. This is a fancy, deep rich diamond with moderate orange accents.

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Joshua J Fine Jewelry

Brown diamonds are beautiful, and they vary in their intensity of color and warmth. What adds to their beauty are the accents of different color. Brown diamonds—in fact, colored diamonds in general—usually have more flashes of colored light than colorless diamonds. Their accents can range from pink, red, orange to even green. It gives them depth and adds to their romantic allure.

They are also versatile, depending on the jewelry setting. The ring from Joshua J Fine Jewelry above is elegant and classic, while this gorgeous bangle from Dilamani is fun and modern:

Brown and white diamond bangle, by Dilamani.

Brown and white diamond bangle, by Dilamani.

Bryan Aderhold, CG, owner and president of Nash James Enterprises LLC, sells brown diamonds and is a fan of their warm beauty. “Brown is another one of nature’s wonderful hues,” says Bryan. “Brown diamonds prompt images of earthly matter such as trees, soil, falling leaves, and chocolate! When acting as a modifier for other colors such as pink, brown can help to produce some very interesting and desirable color combinations.”

To show how two brown diamonds can vary in look and in their appeal, check out these two stunning examples. The one on the left is a great example of a brown diamond with pinkish accents, and the one on the right is a fancy dark brown. Both are lovely; it boils down to a matter of preference. The one on the left would look terrific in a rose gold setting and the one on the right would rock a yellow gold setting.

To learn more about brown diamonds, and how they differ from their famous, colorless cousin, click this infographic created by AGS Laboratories. It’s filled with fun and exciting facts about diamonds, and further explains what makes them so rare and unique.

brown-diamond-infographic-1
To find an American Gem Society jeweler near you who can help you find a brown diamond to add to your jewelry collection, click here. Please also ask your AGS jeweler to show you a diamond with the Colored Diamond Document from AGS Laboratories!

3 Gemstones That Sparkle for the 4th of July

By Robin Skibicki

Dilamani

Ruby, diamond, and sapphire brooch by Dilamani.

The American Independence Day—or the Fourth of July—is when we celebrate our country’s freedom and the adoption of the Declaration of Independence. It’s also considered the height of summer!

It’s a time for family reunions, barbeques, picnics, parades, and the much-anticipated fireworks displays. On this day, we proudly display our nation’s colors: red, white, and blue.

Fun Fact: More than 14,000 firework displays are put on across the country on the Fourth of July!

But don’t let those fireworks grab all the attention. Create your own sparkle-fest with three gemstones that will beautify your patriotic style. We’re talking about rubies, white diamonds, and blue sapphires!

In honor of the holiday, we’ve picked a few designs by our American Gem Society members that feature one of the three, aforementioned gemstones. Click on each image below to get a closer look.

Red Rubies

 

White Diamonds

 

Blue Sapphires

 

May your Fourth of July celebration be sensational, safe, and full of sparkle! To find an AGS-credentialed jeweler near you, visit http://www.ags.org/findajeweler.