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.

 

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 Trends From This Year’s Red Carpet

The highly-anticipated award season may be over, but keep these glamorous ideas in mind for your next special event! Hair jewelry, drop earrings, statement necklaces, a mix of vintage and modern, and of course, diamonds, were big at the Oscars.

Here are a few pieces from American Gem Society members that will surely turn heads!

 

Visit any American Gem Society-credentialed jeweler to find a Red Carpet-worthy style that’s right for you! www.ags.org/findajeweler

 

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.

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.

Gemstone Spotlight: Tanzanite

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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!