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!

Color Comes Into Play with October’s Birthstones

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Opal and tourmaline from Gem 2000.

When it comes to color choices, October’s birthstones give you some amazing choices. Whether you choose opal or tourmaline, you’ll get a display of exciting and intense 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.

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

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.

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.

 

If you are shopping for opal or tourmaline jewelry, click here to search for an American Gem Society (AGS) credentialed jeweler near you.

 

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.

The Merry Month of May

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

“O, the month of May, the merry month of May, So frolic, so gay, and so green, so green, so green!” – Thomas Dekker, Author, (c. 1572–1632).

May is truly the month that really feels like spring, and what better gemstone to have as the birthstone of this blossoming month than an emerald?

 

There’s no other stone that can match the lush, vibrant greens of emerald, truly a springtime favorite. In fact, some people believe the emerald symbolizes renewal and goodness, and that it is a stone that will increase a couple’s love for each other.

The color of lovely springtime emerald can vary in all hues of green, sometimes with a tinge of yellow and others leaning towards the blue-greens. These stones can be light and airy, or deep and dark, and everything in between.

 

Not only that, but it can be highly saturated with this earthy color, making it bright and energetic, just like this time of year.

Emeralds have been prized gems throughout history. Egyptians used the stones for many purposes and claimed a magic slab of the gemstone had “all knowledge” engraved on it. In India, there’s a myth that tells of a firefly that crystallized into an emerald. The Aztecs likened the beautiful color to the plumes of god-like birds.

Those of you who own an emerald (or desire to have one!) are in good company; emeralds were Cleopatra’s favorite gemstone.

 

Emeralds are to be worn with care since they are a softer gemstone than others. But with proper treatment, these stones will last a lifetime.

Emeralds are mined in many locations around the world, from the famous mines in Colombia to the newer mines in Zambia, to others. The finest Colombian emeralds are delightfully bluish-green, richly saturated and stunningly clear.

This spring, while we watch the flowers bloom and the trees sprout, don’t forget your May babies—or their beautiful birthstone, emerald!

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.

Aquamarine: the Cure for the Madness of March

Historically speaking, March is an unusual month. It’s a time of transition, from winter blues to the summertime blue of swimming pools. It’s a windy month, too, and the weather can be fickle as one day is cold and the next is warm. It’s supposed to be the first month of spring, but sometimes it feels like the final month of winter.

Even literature has a conflicted relationship with the month. Shakespeare warned Caesar to “Beware the ides of March” in his eponymous play, “Julius Caesar.”

Despite the ups and downs of March, there is one bright, shining and beautiful factor. Aquamarine.

It’s a word which evokes the sea.

AquaGems

Beautiful aquamarine gems. Courtesy of Suna Bros.

Aquamarine is most often light in tone and ranges from greenish blue to blue-green; the color usually is more intense in larger stones, and darker blue stones are very valuable. This gemstone is mined mainly in Brazil but also is found in Nigeria, Madagascar, Zambia, Pakistan, and Mozambique.

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Aquamarine and diamond ring from Suna Bros.

Like emeralds, this gemstone is a variety of a mineral called beryl. Large stones have been found all over the world, including one stone found in Brazil that weighed over 240 pounds. Aquamarine grows in large, six-sided crystals that can be up to a foot long, making it a great gem to be cut and polished in larger carats for statement pieces.

Not only is aquamarine one of the March birthstones, it’s also used to celebrate 19th wedding anniversaries. It’s a beautiful stone with little or no yellow in it, so it looks great in many settings with different colored metals and gemstones.

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Opal pendant surrounded by aquamarine and diamonds. From Yael Designs.

First, visit an AGS jeweler, who will be happy to help you pick out the perfect piece. Next, look at the stone’s cut. Since aquamarine can be very lightly colored (and sometimes appear almost colorless), the cut is very important to the overall appearance of the stone and how saturated, or even, the color appears.

Of course, choose the color that most appeals to you, however, it’s generally accepted that lighter colored aquamarines are less valuable than the stronger, deeper hues of blue or blue-green.

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Aquamarine and diamonds in a gold setting.
From Erica Courtney Jewelry

Next, take a look at the stone’s clarity. Most cut gems do not have inclusions that are visible to the eye, and some rarer or more expensive aquamarines are available without visible inclusions, as well.

Since aquamarine crystals can grow to be quite large, larger cut gemstones are possible to purchase as a part of beautiful statement pieces. While you may not be looking to buy in that range, even smaller aquamarines make for lovely solitaires or companion jewels in larger pieces.

Ready to see aquamarine up-close and in person? Find an AGS Jewler here. Just don’t forget to bring your jacket. . . or not. It’s March, after all. Who knows what the weather will be like?

Gemstone Spotlight: Tanzanite

tanzanite-UCG

Pear shape tanzanite and diamond ring by United Color Gems.

We often come across a gemstone that inspires us to learn more about its origins and history, as we search out jewelry designs that feature it. Today’s blog spotlights the alternative birthstone for a month other than this one, December. We’re referring to 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.

Zoisite had been around more than a century and a half before this rare blue variety was found in 1967. Trace amounts of vanadium, mixed with extreme heat, cause the blue color – which ranges from pale blue to intense ultramarine with violet undertones.

Due to pleochroism—an optical phenomenon in which a substance displays different colors when seen from different angles—tanzanite 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.

Tanzanite is still only found on a few square miles of land in Tanzania, near majestic Mount Kilimanjaro. Its price and availability are directly tied to mines in this region.

Between its deep blue color and its limited supply, tanzanite is treasured by many—whether you happen to be born in December or not!

 

If you’re drawn to the eye-catching blue, violet, and purple hues of tanzanite, contact an AGS credentialed jeweler near you to find a design that best suits you!

August’s Trio of Distinctive Gemstones

It’s been a year since spinel was added to August’s birthstone line up. Those celebrating a birthday during the eighth calendar month now have three gemstone choices: peridot, sardonyx, and spinel.

Spinel

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Blue spinel by Gem 2000.

For those who are still unfamiliar with spinel, it is often assumed to be other gemstones, like ruby or sapphire.  Cobalt blue, like the one above, is one of the most desired colors. But it can be found in a variety of colors, such as the much coveted red, as well as black, violet blue, greenish blue, grayish, pale pink, mauve, yellow or brown. Spinel can also be found in various cuts, like octagons, trillions, squares, rounds and fancy shapes, like ovals, pears, and cushions.

No matter what the shape, spinel is spectacular! Take a look at these designs by our AGS members. Click on the images for a closer view.

 

Peridot

peridot-Gem2000

Peridot by Gem 2000.

The verdant peridot is the gemstone most commonly associated with August. Peridot’s recognizable green hue could sometimes vary from yellowish-green to olive to brownish green, contingent on how much iron is present. Yet the finest peridot is a brilliant green without any hints of brown or yellow.

Our AGS members will help you find the perfect peridot for you! Click on the images for a closer view.

 

Sardonyx

Sardonyx

Since as far back as Roman times, sardonyx has been highly valued as a stone representing strength, courage, happiness, and clear communication.

The unique reddish, zebra-striped banding of sardonyx stands out beautifully when the stone is smoothed, so it is often cut in cabochon and worn as beads or featured in an eye-catching pendant or ring.

Sardonyx makes a great gift for those born in August who want something a little different than the traditional birthstone. Readily available and relatively inexpensive, sardonyx makes an affordable addition to anyone’s collection.

If you’d like to add spinel, peridot, or sardonyx to your jewelry wardrobe, contact a credentialed AGS jeweler near you!