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!

September is for Sapphires

sapphiremulti003As we turn our calendars to September, we start thinking of things like heading back to school, indulging in a pumpkin spice latte, and planning our fall fashions. For those celebrating a birthday in September, they’re thinking of their birthstone: the 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!

Carelle

Carelle

The Whirl Sapphire Bangle by Carelle is 18k yellow gold with 1.06ct sapphire.

 

 

Michael Schofield & Co.

MichaelSchofield

Yellow sapphire and diamond earrings by Michael Schofield & Co.

 

 

Setaré

Setare

Sri Lankan sapphire earrings mounted in platinum and framed by diamonds, by Setaré.

 

 

Yael Designs

Yael

Yael Designs’ two-tone 18k gold pendant featuring a 1.59 carat pink sapphire, framed by pink sapphires and ideal cut diamonds.

 

Gumuchian

Gumuchian

Gumuchian’s Cloud 9 earrings are 18kt white gold set with blue sapphires and diamonds.

 

 

Ricardo Basta Fine Jewelry

RicardoBasta-Lilac

Lilac sapphire ring designed by Ricardo Basta Fine Jewelry. It’s surrounded by two diamonds and set in platinum.

 

 

Suna Bros.

Suna-StarSapphire

Star sapphire surrounded by diamonds, designed by Suna Bros.

 

AGS Member Spotlight: Suna Bros.

By Randi Molofsky

Aron&JonWhen investing in a piece of fine jewelry, there’s no better choice than a brand with long, distinguished heritage that is known for exemplary craftsmanship and customer service. Enter New York-based Suna Bros., jewelers that do classics better than anyone else in a variety of styles featuring exceptional diamonds and colored gemstones. We spoke to Danielle Barber, Suna’s Director of Creative and Marketing, to find out why its collections, all made in New York City, are still so coveted after more than eight decades.

Suna Bros. has an over 80-year tradition and is a family business, how does that play into the day-to-day workings of the company?

Both Aron and Jonathan Suna are dedicated to the success of Suna Bros. They are involved, truly involved, in every facet of daily business. They’re in early, stay late and work in manufacturing, customer service, design, stone buying etc. Since every Suna piece is crafted in the workshop in our NYC headquarters, they’re often working with our master jewelers or discussing new styles with our designer. They’re also always accessible to Suna retailers, many whom have had long-standing relationships with them, and they’ll work directly with our clients on special orders or requests. It’s inspiring to see such a level of pride and dedication.

Suna is exceptionally great at creating classic, timeless settings. What are some of the most popular styles that the company makes today?

Aron and Jonathan’s father, Kenneth, started Suna Bros. specializing in finely made channel-set wedding bands. Created with that original, old-world aesthetic, these bands remain popular today. The quality is unrivaled: each is individually crafted from start to finish with beautifully hand-cut azures and hand-set diamonds. Classics! Our platinum and pavé diamond styles are perennial favorites as well, especially one ring in particular with 2.20cts. of diamonds.

R6983P-HiRes

You must have a great jewelry archive!  Are there any specific pieces that have been made for many years?

Absolutely, but one piece in particular comes to mind: the Suna starfish. For over 40 years, our small pavé starfish pin has rode the wave of top selling items. It’s become a Suna icon.  We’ve since added complementary larger and smaller pins, pendants and earrings, but the entire starfish collection is based on that one piece.

P7250P

Big, rich colored gemstones are back and more popular than ever. Which are you loving right now?

We are loving color!  The Suna spectrum has been shining with all kinds of gems. We’re especially enamored with tourmaline and its amazing palette. We love them all: paraiba, African paraiba-types, rubellites, greens and incredible pinkish peach hues. It’s impossible to choose a favorite.

Tell us about your Couture collection – is there a recent piece or one that’s being made that you can share with us?

We’re building more and more upon our color collection of one-of-a-kind styles. One gem in particular stands out: a gorgeous 12-plus carat cushion-shaped, African paraiba-type tourmaline. It is a magnificent gem. We’re hoping to finish a ring by the end of May, just in time for Couture, the most exclusive U.S. fine jewelry trade show of the year that takes place in Las Vegas!

Tourmaline

March Birthstone Spotlight: The Tranquil Aquamarine

By Robin Skibicki
Aqua2There are two birthstones that represent the month of March: aquamarine and bloodstone. Both are beautiful and unique gems, but aquamarine is currently the most popular of jewelry designers and wearers.

The aquamarine is a member of the beryl family—same as the emerald—and its colors can range in tones from colorless pale blue, to blue green or teal. The larger the stone, the more intense the color. The most valuable gemstones come from Brazil, but is also mined in Nigeria, Madagascar, Zambia, Pakistan, and Mozambique.

Aqua3This gemstone was believed to protect sailors, guaranteeing a safe voyage ahead. It is said its serene colors can cool the temper, allowing the wearer to be calm and levelheaded. This leads to heightened awareness, better communication, and the ability to retort with a quick response.

The healing powers associated with this stone are believed to cure ailments of the liver, jaws, stomach and throat. The transparent aquamarine was once used to make eyeglasses and lenses.

Now that you know a little more about these brilliant blue beauties, here are a few exquisite examples of how designers showcase the gorgeous gem.

An 18K white gold stunner by AG Gems, with an 9.59 carat aquamarine
flanked by blue sapphires, accented by diamonds.

AG-gems

Aquamarine and diamond pendant, a new addition to
Jye’s International Inc. Luxury Collection.

JYE-aquamarine and diamond pendant

Elegant dangle earrings by Spark Creations, featuring aquamarine and diamonds.

Spark-aquamarine

A glistening collection of aquamarine favorites by SUNA Bros.

Suna

A diamond swan and garnets frame a soothing, 75.59 carat aquamarine.
The Swan Lake pendant by Yael Designs.

SwanLake-Yael

To learn more about aquamarine, visit https://www.americangemsociety.org/birthstones.