Last updateWed, 29 Mar 2017 1pm

Diana Jarrett

The Story Behind the Stone: Diamond & gemstones cut to push light performances

Jarrett FebruaryTransparent gemstones and diamonds are magnets of light; at least that’s the general idea. Cutting techniques and facet pattern designs have evolved over time with one particular goal at the top of a short list; push that stone to sparkle plenty.

The gemstone certainly has a part to play in this effort. Stones with larger numbers on the Mohs scale have greater ability to achieve that sparkling phenom. The higher the Mohs ranking, the harder the stone, and the better it will take a polish; all paramount to its ability to glitter from way across a crowded room.

Key to these gems’ desirability is fire and scintillation. The term fire refers to a stone’s ability to split light into all the spectral hues. The phrase used in gemology for fire is dispersion. The most well-known stone noted for its dispersion is diamond; but several colored gems are pretty impressive in that department too; like zircon, demantoid garnet, and lesser known, but highly collectible, sphene and sphalerite.

Scintillation is a separate deal altogether, and refers to flashes of light occurring when a gem or diamond is moved in the light. Scintillation’s disco-ball effect comes from the lively display of reflections seen bouncing off polished facets. These reflections may be white or have color. In the case of colored gemstones, they may actually produce a brighter hue than the stone’s body color. Occasionally these color flashes will exhibit a secondary hue; flashes of orange and yellow may bounce off a spessartite garnet, for example.

Zak Adourian, a developer of specialized gemological imaging instruments, www.displaystec.com, is expert in researching and analyzing the effect of fire, dispersion and scintillation. His proprietary tools are used by leading members of the diamond and gemstone trade to demonstrate their stones’ best attributes. “Gems are beautiful when they scintillate. That appealing sharp light-shift from facet to facet is eye-catching when the gem or jewelry item moves,” he explains.

Even within the industry, the importance of precision cutting is not always understood as critical to the stones’ ability to perform. Adourian clarifies, “When the stones are newly cut, the edges are razor sharp where the facets meet and that’s important to scintillation.”

Jarrett February 1But he also sites examples of when the crisp look is compromised. “Unfortunately by carelessness or simply ignorance when polishing a piece of jewelry like a ruby ring for example, one can polish the ring and remove minute amounts of metal. But that also happens to the stone in that jewelry.” Not only does it take away some of the gem material making in lighter in carat weight, Adourian warns, but “it ‘kills’ the sharp edges. With rounded edges, the light bends and makes the gem look less appealing. The light does not jump from facet to facet like it should. It looks more like sugar candy.”

So there’s a right way and a wrong way to repolish the metal prongs without the unintended consequences of dulling the stones’ brilliance. Louie Alam, designer and owner of Los Angeles-based Louie B Designs, says his jeweler-father Bob Alam taught him in his first weeks of apprenticeship how to take special care when working with softer gems. “We work on the prongs first and polish the metal before mounting the stone. Then we carefully retouch the prongs after mounting if needed.”

The main goal of gemstone cutting and polishing is to optimize the light performance. So preserving the integrity of a well cut stone needs to remain top-of-mind when repair work is being conducted on a piece.

It should certainly be a strong selling point in the presentation of fine jewelry in a retail setting. When presenting an item, Adourian says, “The jeweler can help a customer appreciate the value of well-cut stones on a piece of jewelry’s overall appearance.” Even after some tutorial, the customer may not remember all the details, but you will have helped them to train their eye to better assess value components in a piece of fine jewelry. In the end, you will help them to know what they like, Adourian points out. “A well cut stone is one that pleases the eye.”

Award winning trade journalist and gemologist Diana Jarrett is a Registered Master Valuer Appraiser and a member of the Association of Independent Jewellery Valuers (AIJV). She’s a popular speaker at conferences and trade shows. Jarrett writes for trade and consumer publications, online outlets, her blog: Color-n-Ice, and www.jewelrywebsitedesigners.com. Contact her at This email address is being protected from spambots. You need JavaScript enabled to view it., visit her website at www.dianajarrett.com, and follow her on Facebook and Twitter (Loupey).


More than just a pretty facet

Jarrett RingIt could be argued that the last decade’s economic free-fall changed peoples spending habits forever. After licking their wounds, consumers gained a more realistic grasp of the true value of a dollar. And that bodes well for jewelry aficionados. Shrewd collectors are responsible for some of the most jaw-dropping prices realized for jewelry at auction today. Because real value and rarity is the target to aim for when it comes to gemstones.

Dig This!

Jarrett ChelseaEnergetic and exploratory by nature, Chelsea Thompson, owner of Schurz, Nevada-based RockChuck, and fellow prospector John Keady have been digging around the western United States for several years. Prospector, mine owner and jewelry maker, she does it all from the ground up. You can’t argue that prospecting is glamorous, but it does score high in the thrill-of-discovery department. “We have been so amazed at the size of crystals we’ve been pulling out of the earth. They are incredible,” Thompson reports. 

The Story Behind the Stone: Another source, another phenomenon

Jarrett NovemberFor bona fide gem connoisseurs, nothing compares to the hypnotic color change variety witnessed in the alexandrite stone. This rare and valuable jewel is actually a chrysoberyl that naturally changes color from daylight to candlelight. The striking and mysterious effect is infinitely repeatable. People routinely described this stone as an emerald by day and a ruby by night. The name Alexandrite (for Czar Alexander II) is a romantic nod to its original discovery in Russia’s Ural Mountains in 1830.

If that’s not enough of a light show for you, the stone occasionally produces a cat’s eye effect when cut en cabochon. Negative crystal inclusions and rutile silk account for its ability to create a cat’s eye phenomenon from a piece of alexandrite rough.

The Story Behind the Stone: Beryl of Sunshine

Beryl, a celebrated and ancient gem species counts emerald, aquamarine and the delicate pinky-peach morganite in its lineup. There’s also the elusive red bixbite, the priciest one, and an extremely rare jewel to boot. But one captivating variety hasn’t been around for eons. Early in the 20th century, German miners in Namibia digging for aquamarine happened upon a rich beryl pocket that exposed stunning saturated golden crystals. Previously unknown, they’d discovered yellow beryl. After the initial unearthing, yellow beryl deposits found elsewhere produced crystals in warm orange-ish shades or with a slightly greenish back color that would expand the new gemstone cache.

The Story Behind the Stone: What’s shape got to do with it?

Jarrett Sept earsSometimes the story is all about the stone. Sometimes it’s all about the designer. But this time we bring you a designer who is working with a fusion of Edwardian era motifs interpreted for the very modern lady. The result is a completely new shape of jewelry that is at once appealing but with a surprising twist.

How many dangling pendant ear bobs can a woman wear? There is something infinitely appealing about the clip style earring. Its profile hugs the curves of the ear and in the transaction create sparkling bookend style high-drama for the lady. There is no other earring form with that potential to optimize the light reflecting sparkle aimed back towards the cheeks and chin like this particular shape.

The Story Behind the Stone: Such a deal

Jarrett pitReal estate listings are everywhere you look. That means you can expect some odd-ball properties to come onto market from time to time if you look long and far enough. Here’s one you may not have seen coming. We’ve never seen this come on the market before.

125 Year Old Property

A recent Financial Times (ft.com) headline read: De Beers to sell legendary Kimberley Mines. Readers learn that it is “set to end more than 125 years of diamond mining history.” The offering details the unloading of an iconic kingpin responsible for more than a century of mining and trading at that location, the Kimberley Mine.