It’s Only Natural

By Robin Skibicki

Not all gemstones are minerals with a crystalline structure. In fact, some were formed through biological processes of living organisms, such as plants and animals. These natural beauties are referred to as organic gemstones and include several varieties that are important to the gem trade. We’re talking about pearls, coral, amber, ammolite, and shell, just to name a few.

Pearls

Pearls are pretty much perfect for any occasion. It doesn’t matter if you’re dressed in silks and satins or khakis and jeans, they go with everything! There are several types to choose from, like freshwater or saltwater, natural or cultured, with such varieties as Akoya, Keshi, South Sea, and Tahitian.

 

Coral

There are hundreds of species of coral throughout the world, but only a few are used for fine jewelry. Corallium japonicum and Corallium rubrum are two varieties of red coral commonly used to produce jewelry, and Antipatharia, a species of black coral prized for its lustrous, black appearance after polishing.

 

Amber

Amber had its moment in the spotlight when it appeared as a source for “Dino DNA” in the movie, Jurassic Park. This fossilized resin of ancient tree sap dates back 25 to 50 million years, with some of the oldest known material dating back 290 to 350 million years ago. Amber comes in over 300 different shades, with the most common colors being honey, green, cherry, cognac, citrine, and butterscotch.

 

Ammolite

Ammolite is an iridescent gemstone material that comes from the fossilized shell of extinct squid-like creatures called ammonites. They only come from one place: Alberta, Canada. Although they have been forming for millions of years, ammolite first appeared in jewelry in the 1960s and was recognized in 1981 as an organic gemstone.

 

Shell

Shell has been used for decorative purposes for centuries and was most likely the by-product of the search for food. It’s been used for everything from buttons to knife handles, from cameos to necklaces. In jewelry design, the two most familiar types of shell are abalone and mother-of-pearl.

Interesting facts: Abalone is composed of mother-of-pearl. Mother-of-pearl is called nacre, which makes the outer layer of pearls.

 

Visit an AGS-credentialed jeweler near you and ask them to show you some organic gemstones!

 

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!

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!

Father’s Day Gift Ideas for Every Dad

By Robin Skibicki

Father’s Day is this Sunday, June 19. If you haven’t thought about a gift for your dear Dad, we have a few ideas to get your creative juices flowing. Just like Mom, Dad appreciates a gift of quality that will last a lifetime. Styles and trends may come and go, so be sure to find something that fits your Dad’s personality and lifestyle.

The Fun & Funky Father

This is the Dad who always has a fun story to share, a silly joke to tell, and got a kick out of embarrassing you when you were a kid! The Triangle Puzzle Ring by Mark Schneider matches this fun personality. Its two-tone 14k white and yellow gold with 0.205ctw diamonds.

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Looking for something different and slightly exotic? The Legends Naga Dragon Head bracelet by John Hardy is sterling silver and 18K bonded gold. The eyes are set with African rubies.

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The Fan-atic Father

If your Dad is a sports fan, he’ll cheer for these two sporty styles by Lashbrook Designs. Die-hard baseball fan? Go with the cobalt chrome 8mm band with baseball “stitching.” Dedicated basketball fan? Pick the titanium 8mm domed band with the basketball pattern.

The Fit Father

For men who live a very active lifestyle, purchase titanium jewelry. It’s the hardest of the metals, therefore more scratch, dent and bend resistant. Hearts On Fire designed this durable yet lightweight gray titanium ring. It’s highlighted by a cable rope running through the center, and one small, single diamond.

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The Factual Father

He likes to keep things simple. John Hardy designed a reversible, flat chain bracelet that’s sterling silver on one side and bronze on the other. Who doesn’t appreciate the versatility and convenience of reversible jewelry?

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Two-toned designs are very popular because they work with any look. The Grand Signature Bracelet by Ed Levin Jewelry is sporty, comfortable, classic and bold. No fuss, no muss.

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The Formal Father

The French cuff, whether worn with a business suit or a tux, always lends a formal feel to any look. Add a pair of stylish cufflinks, like these sterling silver and genuine onyx links by Stuller, for a finished touch!

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Dad deserves some bling, too! This design by Unique Settings of New York is timeless and stylish, with just the right amount of sparkle.

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The Futuristic Father

He’s all about technology. The car, the appliances, the gadgets—all must be wired into something…and each other! Whether you understand it or not, show your support for his love of innovation.

Royal Asscher carries a unique design collection called Stars of Africa. They have encased their exquisite diamonds and colored gems inside a dome, giving them freedom to move and sparkle. Dad ought to be fascinated with these sterling silver cufflinks housing blue sapphires.

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Dad is going to think this is cool! Steven Kretchmer designed a tri-band ring using Polarium™, their magnetic platinum alloy. The three 7.5mm magnetic bands have a matte finish with rounded edges, with the middle component featuring a stripe of 24k crystallized gold inlay.

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Need some more ideas? Use our online Find a Jeweler search to locate an AGS credentialed jeweler near you. Our highly trained and educated jewelers will help guide you through the buying process and answer any questions you may have. Enjoy celebrating this day dedicated to Dad!