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!

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.

Idolite earrings

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!

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!

Spinel Named Third Birthstone for August

AugustBirthstonesWe have a birthday present for those born in August: the spectacular spinel has been added to your month’s birthstone lineup! August now joins June and December as the only months represented by three gems. The original birthstone for August was Sardonyx, and then peridot was added, becoming August’s primary gem. Without further ado, let’s welcome the spinel!

Spinel

4908The spinel is often assumed to be other gemstones because it tends to resemble either a ruby or sapphire. In fact, some of the most famous rubies in history have turned out to be spinel. But its distinguishing features, like its octahedral crystal structure and single refraction, are what sets it apart from other gems. Spinel also has a lower Mohs hardness than ruby and sapphire.

Significant deposits of spinel have been found in Cambodia, Myanmar, Sri Lanka, and Thailand. It has also been found in Afghanistan, Australia, Brazil, Madagascar, Nepal, Nigeria, Tadzhikistan, Tanzania and the U.S.

Vivid red is the most desirable color of spinel gemstones, followed by cobalt blue, bright pink and bright orange. The more affordable stones are often those with paler colors, like lavender. You may also find spinel in black, violet blue, greenish blue, grayish, pale pink, mauve, yellow or brown. So many choices!

When shopping for spinel, a good quality stone should have no visible inclusions. The more inclusions, the less valuable the stone. Spinel can be found various cuts, like octagons, trillions, squares, rounds and fancy shapes, like ovals, pears, and cushions.

Below is a collection of designs featuring the spectacular spinel!

AG-Gems-PurpleSpinel-ring


AG Gems designed this ring featuring a natural purple spinel flanked by two natural half-moon cut violet spinels, set in 18k white gold, and accented by pink sapphires and diamonds.

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Sterling Silver Classic Chain Medium Bracelet with pink spinel by John Hardy.

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Omi Privé 18k yellow gold ring featuring a 3.27 carat oval spinel, round spinels, and round diamonds.

Peridot

Natural Green Peridot

The signature green color of peridot comes from the composition of the mineral itself—rather than from trace impurities, as with many gems. That is why peridot is one of few stones that only comes in one color, though shades may vary from yellowish-green to olive to brownish green, depending how much iron is present.

Most of the world’s peridot supply comes from the San Carlos Reservation in Arizona. Other sources are China, Myanmar, Pakistan and Africa.

Also known as “the Evening Emerald” because its sparkling green hue looks brilliant any time of day, peridot is said to possess healing properties that protect against nightmares and evil, ensuring peace and happiness. Babies born in August are lucky to be guarded by peridot’s good fortune.

Peridot can be assessed with the same 4Cs criteria as diamonds—using Color, Clarity, Cut, and Carat weight to determine value. The finest peridots have a lovely lime green hue without any hints of brown or yellow. Quality gems have no inclusions visible to the naked eye, though dark spots may be evident under a microscope. When you look closely, due to double refraction, you may see two of each facet on a peridot.

Whether you’re shopping for an August birthday or a 16th wedding anniversary, be sure to visit an AGS-certified jeweler. They will help you find the perfect peridot design, like those pictured below!

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Whirl Peridot and Burnished Diamond Ring by Carelle.

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Oxidized Sterling Silver and 24k Gold “Candy” Earring with Oval Peridot Cabochon, by Lika Behar Collection.

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Erica Courtney presents 18k Yellow Gold “Chevron” Ring
Featuring a 9.81ct Peridot, Accented with 1.04ctw diamonds.

Sardonyx

Sardonyx combines alternating layers of sard and onyx—two types of the layered mineral chalcedony—to create a reddish zebra-striped stone with white bands.

Sard ranges in color from yellowish red to reddish brown, depending how much iron oxide is present. Sard is easily confused with carnelian, another type of chalcedony that is slightly softer and lighter in color.

Sardonyx, like onyx, shows layers of parallel bands—instead of the chaotic, curved bands that compose agate, another type of chalcedony.

The finest examples of sardonyx, which display sharp contrasts between layers, are found in India. Other sources include Brazil, Germany, Czechoslovakia, Madagascar, Uruguay, and the United States.

Used as a stone of strength and protection since ancient times, sardonyx is associated with courage, happiness, and clear communication. Some believe that placing sardonyx at each corner of a house will grant protection against evil.

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

The qualify factors of sardonyx are not as clearly defined as other gems like diamonds, so ask an AGS-certified jeweler for help selecting good stones. Generally, the 4Cs still apply.

Sardonyx is widely available and moderately priced in sizes up to 10 carats. The most common cut is cabochon, though it is popularly carved into cameos, intaglios, inlays and broaches to emphasize the contrast between layers.

Artificial and imitation sardonyx has been produced from common chalcedony and plain agate as far back as Roman times, according to writings from first-century naturalist, Pliny. Some gems are also stained with iron oxide pigment or treated with nitric acid to enhance color. These enhancements make stones less valuable than natural sardonyx, so watch for possible imitations when buying these gems.

Want to know more about birthstones? Click here to see all birthstones by month on the American Gem Society website.

Get Ready for Rubies!

For those born in July, the ruby—the king of precious stones—is your birthstone.

Ruby is the red variety of the mineral corundum, colored by the element chromium. All other colors of gem-quality corundum are called sapphire, which means color is key for this royal stone.

The chromium that gives ruby its red color also causes fluorescence, which makes rubies glow like a fire from within. Paradoxically, chromium is also what makes this gem scarce because it can cause cracks and fissures. Few rubies actually grow large enough to crystallize into fine quality gems, and these can bring even higher prices than diamonds.

Accordingly, the name “ruby” comes from rubeus, the Latin word for red. In ancient Sanskrit, ruby translated to ratnaraj, which meant “king of precious stones.” These fiery gems have been treasured throughout history for their vitality.

Tough and durable, ruby measures 9 on the Mohs scale. Diamond is the only natural gemstone harder than ruby. Ruby’s strength and red fluorescence make it valuable for applications beyond jewelry. Both natural and synthetic rubies are used in watchmaking, medical instruments and lasers.

Due to its deep red color, ruby has long been associated with the life force and vitality of blood. It is believed to amplify energy, heighten awareness, promote courage and bring success in wealth, love and battle. Many cultures regard the ruby as a symbol of love and passion, and have long been considered the perfect wedding gem.

Rubies make wonderful gifts for a July baby, or anyone marking an important milestone, like a 15th or 40th wedding anniversary. If you’re in search of rubies as a gift or to add to your jewelry wardrobe, visit our Find a Jeweler search for an AGS credentialed jeweler near you.

In the meantime, relish in these stunning designs featuring the ravishing ruby!


Gregg Ruth

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The Tropez Pendant by Gregg Ruth features 2.48Cts of rubies and 0.20Cts of white diamonds.


Armadani

Armadani-rubyearrings

Armadani designed these lovely ruby and diamond flowers studs set in 18k white gold.


Michael Schofield

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Michael Schofield designed this fantastic brooch of rubies and diamonds set in 18k white gold.


Lika Behar

LikaBehar-RubyPendant

The Rosalie Necklace by Lika Behar features a rose cut ruby slice surrounded by champagne diamonds, and set in 24k gold and oxidized silver.


AG Gems

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These earrings by AG Gems feature marquise, cushion and round cut rubies cascading down 18k yellow gold swirls set with diamonds.


OMI Privé

OmiPrive-bracelet

OMI Prive designed this exquisitely detailed ruby and diamond bracelet, set in platinum with 18k yellow gold.


Christopher Designs

ChristopherDesigns-rubyring

The ruby in this ring design by Christopher Designs is 3.64ct, surrounded by 1.02ct Crisscut Round diamonds.