Colored Gemstones

Gemstone Products

Diamond Council of America ©2016

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Colored Gemstones 3 1

In This Lesson:• Enticing Choices

• Gem Minerals

• Treated Gems

• Synthetics

• Imitations

• Assembled Products

ENTICING CHOICES It could be said that the gem and human w orlds have developed

together over thousands of years. The earliest gem materials wereby-products of the search for food and the struggle for survi val.These included pearl, shell, and ivory. Crystals and pebbles withstriking shapes and vivid colors were also found as primitive culturesexplored their surroundings. Eventually people began to enhance andimitate the beauty they saw in gems. In modern times, they ulti-mately learned to re-create it.

For many centuries, the evolving activities of discovery, trade,art, science, and technology gradually added to the number andvariety of gems that were available. Within the last few decades,however, those same forces have come together to create a rapidlygrowing galaxy of enticing choices for consumers. As a result,today’s gemstone products, and the jewelry in which they appear,reflect all the rich diversity of contemporary life.

As a jewelry sales professional, it’s essential for you to know andunderstand these products. The distinctions among them are criticalin every aspect of your work. In sales presentations, for example,solid product knowledge serves as a foundation for representationand disclosure. It’s also the basis for explaining the value andmeaning of gems.

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Gem materials werean important part ofearly culture.

Cover image courtesy Jean-François Albert.

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You’ve already learned that the gem world includes minerals,organic materials, treated gems, synthetics, imitations, and assem-bled products. In this lesson you’ll begin to take a closer look atmost of these. Lesson 4 will explain factors that determine theirvalue, while Lessons 5 and 6 discuss cultured pearls and otherorganic gems.

For now, the emphasis will be on providing clear descriptionsand highlighting basic differences. As you move further ahead inthe course, you’ll see how product fundamentals apply in sellingas well as other job responsibilities such as care and cleaning,merchandising, and display.

Lesson Objectives When you have successfully completedthis lesson, you will be able to:• Explain how gem minerals relate to each other.

• Define the most common types of treatment.

• Describe the main methods for synthesizing gems.

• Recognize how imitations and assembled products are used.

Minerals are also part of the gemworld. Although prized as specimensfor their own unique beauty, most areeventually cut into gems for jewelry.

JA® SPC SKILLSIf you’re participating in the JA®

Sales Professional CertificationProgram™, this lesson presents infor-mation related to the following SkillAreas:

PRODUCT KNOWLEDGE• Colored Gemstones• Pearls• Disclosure• History of Jewelry• Designer & Brand Name Jewelry

SERVICES AND GUARANTEES• Warranties and Guarantees• Store Service Programs

SERVICE DEPARTMENT

CUSTOMER SERVICE• Building Customer Relations

SELLING PROCESS• Customer Needs• Building the Sale• Closing the Sale

SELLING TOOLS OPERATIONS• Store Maintenance• Merchandise Maintenance

POINT OF SALE PROCEDURES• POS Customer Development

RISK MANAGEMENT• Security

PROFESSIONAL STANDARDSAND EXPECTATIONS

BUSINESS ETHICS• FTC Guidelines• Trade Practices

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GEM MINERALS Most natural gems are minerals that were created by

Earth’s rock-forming processes. Scientists have identi-fied more than 4,000 different kinds – or species – ofminerals. many of which are valued by collectors. Ofthese, fewer than 100 have the beauty and durability tobe considered gems. Only about 20 mineral speciesappear often in jewelry stores, and just three account for more than 95% of all gemstone sales in v alue.Those three are diamond, beryl (BER-al), and corundum (ka-R UN-dum).

Everyone has heard of diamond, but the other two will probably not sound familiar to mostcustomers. That’s because beryl and corundum are species names, and gems belonging to those speciesare usually sold under better-known variety names. Beryl varieties include emerald and aquamarine.Corundum has two main varieties – ruby and sapphire.

Emerald is a variety of thespecies beryl.

Photo courtesy Tino Hammid.

Ruby and sapphire arevarieties of the speciescorundum.

Photo courtesy John Buechner.

The garnet group is a familyof closely related species.

Garnet collectioncourtesy of Janice Mack.

To understand these distinctions, you need to know a little about howminerals are scientifically classified:

• Species – A species is a mineral type that’s defined by the combina-tion of chemical composition and crystal structure. Chemical compo-sition is the atomic recipe – the kinds and relati ve quantities of atomsthat make up the mineral. Crystal structure is the w ay in which theatoms are arranged. Corundum’s composition, for example, is repre-sented by the formula Al2O3. That means it’s made of aluminum (Al)and oxygen (O), with two aluminum atoms for every three oxygenatoms. In a corundum crystal the atoms also form a three-dimensionalgeometric pattern that’s described as hexagonal.

• Variety – A variety is a subcategory within a species. Gem varietiesare usually distinguished by color or one of the optical ef fects knownas phenomena. Corundum with a red color is ruby. Corundum of anyother color – not just blue – is sapphire. If there’ s also a star effect, it’sstar ruby or star sapphire depending on the color .

• Group – A group is a mineral family made up of species that areclosely related in composition or structure. Garnets form the mostfamiliar gem mineral group. There are about a dozen species ofgarnets, and half of them produce gems. All garnets have the samecrystal structure, but differ slightly in chemical compositions.

PHENOMENAL GEMS

Phenomenal gems form a special product category that appeals tomany customers. A few are rare and costly, but others are within

reach of even the most modest budgets. They all have some kind ofextra optical effect (besides color) that sets them apart from their moretraditional counterparts.

There are dozens of phenomenal gem varieties. Most, however,show one of the following effects:

• Play-of-Color – This is the rainbow dance you see in opals. Itoccurs because these gems are composed of tiny silica spheres thatbreak up white light into spectral hues. (The spheres are less than10 millionths of an inch in diameter.) Opal is the onlynatural gemstone with true play-of-color.

• Change-of-color – Gems with this effect appear tobe different colors in different types of light. Finequality alexandrite provides an outstanding example.Under a standard incandescent bulb, it appears red.In daylight or fluorescent light, it appears green. Thechange is triggered by shifts in the light’s colorcontent. Alexandrite is a variety of the chrysoberyl

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Lesson 8 describes how gem minerals form, including the conditions that produce species, v arieties,and groups. You can find more information in the Colored Gemstone Compendium. Most customersaren’t too interested in mineral terms and kinships, ho wever, so you usually don’t need to spend muchtime on the subject. Occasionally, though, you can add interest by e xplaining some eyebrow-raisingdetails – like the fact that ruby and sapphire belong to the same species. You might call them “gemsiblings.” If a customer is considering garnets and thinks red is the only choice, you might surprise himby revealing that members of this group occur in other colors, too. (Be ready to sho w examples whenyou spark curiosity, however.)

In every presentation, a top priority is identifying your products. That’s where understanding gemnames and knowing how to use them really counts. Sometimes a single w ord is enough. When you sayruby, sapphire, or emerald, there’s instant recognition. Sometimes it helps to clarify a bit: “This is bluetopaz,” or “pink tourmaline.” At other times you need to be more elaborate: “This bright purple gem isthe garnet variety known as rhodolite.” After such introductions you can provide more information, andyou’ll learn to do this in upcoming lessons. Initially , however, your main concern is making sure thecustomer understands what you’re showing.

Play of color in opal.

Photo courtesy John Buechner.

Change of color in alexandrite.

Photos courtesy Tino Hammid.

species, the phenomenon is often called the alexandrite effect.Other natural gems that can display this dramatic color changeinclude garnet, sapphire, and spinel. One kind of syntheticsapphire also shows change-of-color. This man-made product isinexpensive and widely available. The color goes from purplein incandescent light to green in daylight or fluorescent light.

• Cat’s-eye – This phenomenon is sometimes called chatoy-ancy (sha-TOY-an-see). Another variety of the chrysoberylspecies shows the effect at its best. In cat’s-eye chrysoberyl, ashining band is produced by light reflections from microscopicneedle-like crystals trapped inside the gem. That band gives thephenomenon its name. (To create a sharp cat’s-eye, the gemmust also be cut in the domed style known as a cabochon.) Anumber of other natural gems occasionally display chatoyancy.The most affordable one is the quartz variety called tiger’s-eye.

• Star – This effect is also known as asterism. It has the samecause as chatoyancy: light reflections from needle-like inclu-sions. In a cat’s-eye, however, the inclusions are parallel toeach other. In a star gem, they’re oriented in different direc-tions. So, instead of a single band, you see multiple raysextending from a center point. The best-known examples of thisphenomenon are corundum varieties – star ruby and starsapphire. Asterism sometimes occurs in other gems such asgarnet, quartz, and spinel.

• Moonstone – The phenomenon is technically known asadularescence (AD-ja-lar-ESS-enss). The only natural gem inwhich it’s seen is moonstone, which is a variety of feldspar. Thephenomenon appears as a soft floating glow. The floating glowis sometimes blue, but more often white. The effect is caused bylight reflecting and scattering from different layers in the gem’sstructure.

The Colored Gemstone Compendium includes profiles of alexan-drite, cat’s-eye chrysoberyl, moonstone, opal, star ruby, starsapphire, and tiger’s-eye. There you’ll find more facts you can usein presenting these gems, plus tips for showing them at their best.

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Asterism in star sapphire.

Photo by Tino Hammid courtesy RafcoInternational Gem Corporation.

Adularescence inmoonstone feldspar.

Chatoyancy in chrysoberylcat’s-eye.

Photo by Tino Hammid courtesy RafcoInternational Gem Corporation.

TREATED GEMS Except for fashioning techniques like cutting and carving, almost any artificial process that

improves a gem’s appearance or durability is considered a treatment. Although treatments are some-times controversial, they’ve been part of the gem world since ancient times. Treated gems were foundin the tomb of Egypt’s Pharaoh Tutankhamen (who died in 1325 BC). A Roman book written almost2,000 years ago describes several treatment methods that are still in use today .

Gem treatments developed slowly until the 20th century. When science andtechnology began to supply advanced tools like high-temperature furnaces andnuclear reactors, changes in treatment processes began to come at a muchquicker pace. Our understanding of the chemistry and physics of gems has alsoincreased, and as a result, the variety, sophistication, and extent of treatmentshave grown rapidly in recent decades.

Today, treatments are vital to the jewelry industry. They make beautifulgems more available and more affordable. Therefore, it’s important to knowabout treatments – what they do and on which gems they’re used.

You also need to be able to informcustomers about treatments. You may not be ready to do that,however, until you’ve moved further ahead in this course.Mentioning treatments without knowing how to discuss themproperly can ruin a sale. Lesson 15 will sho w you how tomake disclosure a positive part of your presentations. TheColored Gemstone Compendium will give you all the factsyou need. If you are handling colored gems on a re gular basis,you may want to jump ahead and familiarize yourself with thetypes of treatments and how to disclose them in a positiveway.

For now, as part of this initial product surv ey, here’s analphabetical listing of the most common treatments forcolored gems:

• Bleaching: Using chemicals like hydrogen peroxide or chlorine bleach (sometimes e ven acid) tolighten or remove color or dark surface blemishes. This is a standard procedure for most culturedpearls, either by itself or before color-adding treatments such as dyeing and irradiation. It’s alsocommon for chalcedony, jade, and tiger’s-eye.

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It's important to understand treatments andnecessary to tell customers about them.

Treated gems datingbefore 1300 BC werefound in the tomb ofTutankhamen.

• Coating: Applying a thin layer of some substance to a gem’ s surface,usually to improve or change the color. Coating can also make the polishlook better (in other words, make the surface look smoother). It canimitate or intensify a phenomenon such as asterism, too. Man y differentsubstances are used as coatings – oil, w ax, paint, varnish, plastic, foil,and metallic compounds like those used for mirrors and camera lenses.The treatment is most often seen on imitations. F amiliar examplesinclude glass “rhinestones” with a mirror-like coating on the back.Colorless quartz and topaz are sometimes coated to add surf ace color orcreate iridescence. (Iridescence is the “oil-and-water” colors that appearwhen light is broken up by structural layers.)

• Diffusion: Heating a gem to very high temperature while it’s in contact with selected chemicals.The chemicals penetrate the gem’s surface and actually become part of the crystal, changing itscolor in the process. Depending on the technique that’ s used, the new color can be very shallow(often extending less than 1/100 inch beneath the surf ace), or it may go deeper – sometimes all theway through the gem. Shallow diffusion is most often used on colorless and light-colored sapphires.The chemicals can produce a colored layer of red or blue that is just thick enough to mak e the stonemimic ruby or blue sapphire. Deeper diffusion is usually used on pale sapphires to create a v arietyof more intense colors, including orange, yellow, green, and violet. Deep diffusion can also turn alight-colored sapphire to ruby red. Occasionally, diffusion is used to produce a star ef fect bycreating a layer of needles just below the surface from which light can reflect.

• Dyeing – Adding a chemical coloring agent to improve or changecolor. This is common for translucent and opaque gems such aschalcedony, cultured pearls, jade, lapis lazuli, opal, shell, tiger’ s-eye,and turquoise.

• Filling – Adding a substance to fill a void in a gem. There are twobasic versions of this treatment: fracture filling and cavity filling. In fracturefilling, breaks that reach the gem’s surface are filled to make them less visible.This improves the gem’s appearance. In cavity filling, largersurface openings are filled for the same purpose. If the ca vitiesare large, the treatment also adds weight. Fracture f illingsinclude colorless oils, natural or synthetic resins, and glass.Cavity fillings are usually glass or plastic. Fracture f illing iscommon for emeralds, while cavity filling is most frequentwith rubies and sapphires. Both methods appear less often inother gems. If a coloring agent is added to the f iller, the treat-ment is also considered dyeing.

Diffusion creates a thinlayer of color on thesurface of a gem.

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A cavity in a ruby hasbeen filled with glass.

A filled fracture in a diamond isrevealed by the pink reflection.

• Heating – Using high temperature, usually to improve or changecolor. This is common for many gems including amber, aquamarine,carnelian, citrine, ruby, tanzanite, tiger’s-eye, zircon, blue and yellowsapphire, pink and red topaz, and blue, green, and pink tourmaline.Carefully controlled heating can eliminate needle-like inclusions andimprove the clarity of rubies and blue sapphires. Less often it’ s used tomake the same kind of inclusions grow in order to create or intensify astar effect.

Heat treatment can often be detected by microscopic clues that it lea ves inside the gem. Sometimesdetection takes advanced testing. Please remember that this course isn’ t designed to teach you how toidentify treatments. The objective of this lesson is to inform you that the treatment e xists. Lesson 15 willexplain how to disclose it to your customers.

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From Gemstones,Quality and Value,Volume 1 by YasukazuSuwa.

Impregnated

Impregnated

untreated

Turquoise may bedyed or wax-impregnated toimprove color.

• Impregnation – Applying oil, wax, plastic, epoxy resin, or similarsubstances to fill pores and small surface openings. This process is some-times called stabilizing. It’s similar to coating, but low heat or other methodsmay be used to improve penetration. Impregnation usually improves thegem’s color and the way the polish or surface looks; sometimes durability,too. It also conceals minor blemishes and cracks. This treatment is commonfor coral, jade, lapis lazuli, opal, and turquoise. As with filling, if a coloringagent is added, the treatment is also considered dyeing.

• Irradiation – Exposure to high-energy radiation or bombardment withsubatomic particles to change color. This is routine for smoky quartz andblue topaz. (With topaz it’s followed by heating.) Irradiation is also commonfor red, pink, and purple tourmaline. It’s sometimes used on amethyst andcultured pearls, too.

As you can see from this brief look, the list of colored gems that might betreated probably includes most of those in your sho wcases: amethyst, aquama-rine, chalcedony, citrine, coral, cultured pearls, emerald, jade, lapis lazuli, opal,ruby, sapphire, shell, smoky quartz, tanzanite, tiger’s-eye, topaz, turquoise, tour-maline, and zircon. Those are only the standard treatments and the gems onwhich they’re most commonly used, too! The complete list is much longer andmuch more detailed!

Most treatments are routine and permanent and do not

substantially effect value.

Ruby before and after heat treatment.

SYNTHETICS In Lesson 1 you learned that synthetics are man-made v ersions of

natural gems. They have essentially the same compositions, structures, andcharacteristics as their natural counterparts. You might also say they’rerealizations of the age-old desire to re-create the beauty and w onderhumans perceive in the world around them.

The first experiments in gem synthesis began in the early 1800s. Thatwas soon after mineralogy became a science. Success on a commercialscale came after nearly a century of intense w ork. Since then, however,synthetic gem materials have become part of our technological culture.Besides being set in jewelry, they’re used in electronics, medicine, manu-facturing, science, and even national defense.

So far, more than 1,500 mineral species and varieties have been synthe-sized. Most of these are just for e xperimental or technical purposes,though. Only about a dozen are commonly a vailable in the jewelry

industry. They include the synthetic forms of alexan-drite, amethyst, citrine, emerald, opal, ruby, sapphire,smoky quartz, and spinel. Synthetic quartz is alsoproduced in colors that don’t occur naturally. Someother synthetics – for example, synthetic cubiczirconia (CZ) and synthetic moissanite – are not soldas synthetic versions of natural gems but rather asimitations of natural gems or merely as “lab-createdgems”. Synthetic diamonds have begun to appear onthe market, too.

All of the synthetics developed up to now havebeen detectable. That’s likely to remain true. Manycan be separated from their natural counterparts by

At this point it’s important to recognize that treatment of colored gems is v ery common. In manycases you also have a responsibility to disclose it. You shouldn’t over-react or alarm customers, though.As you’ll learn in Lesson 15, you simply need to kno w what treatments the gems in your inventoryhave undergone. This information is usually provided by your supplier or your buyer. Then you needto inform customers of a treatment if it’s not permanent, if it creates a need for special care, or if it hasa significant effect on value. You’ll find out how to do all of this by the time you f inish the course.

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Synthetic moissonite does nothave a natural gem counter-part.

Most synthetics can be separated from theirnatural counterpart by simple gemological tests.

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simple gemological tests or examination with a microscope.(Natural gems and synthetics have different kinds of inclusions.)For some synthetics, identification might require advanced labora-tory testing, but they will all eventually reveal their origin to theexperienced gemologist.

As with treatments, this course isn’t designed to teach youhow to identify synthetics yourself. Its purpose is to inform youthat these products exist, and to assure you that they can be identi-fied. If you have questions about the gems in your inventory, askyour buyer or manager to answer them for you.

In flame fusion, powdered chemicals are droppedthrough a flame, melted and re-solidified onto arotating pedestal forming a ”boule”.

Graphics courtesy Michael O’Donoghue, A Guide to Man-made Gemstones.

In the pulling technique,the chemicals are meltedand then “pulled” slowlyout of the melt as theycrystallize onto aretreating rod, forminglarge, perfect “boules”.

There are special ways for synthesizing gems like opal and diamond. There are also dozens of vari-ations in basic techniques. Most synthetics, however, can be divided into two categories: melt-grownand solution-grown.

• Melt-Grown Synthetics – The most important methods for manufacturing melt-grownsynthetics are known as flame fusion and pulling. The first is sometimes called the Verneuil (ver-NOY) process. The second is also known as the Czochralski (cho-KRAL-ski) process. (Those arethe names of the researchers who developed the processes in the early 1900s.) In flame fusion,chemical ingredients are poured through a blowtorch flame, which melts them. The melt is allowedto cool and crystallize on a rotating pedestal. In pulling, the ingredients are f irst melted in acrucible. Then a seed crystal is dipped into the melt and slo wly pulled away, growing the syntheticgem as it goes.

In melt growing the crystal growth produces“boules”, carrot-shaped formations

Flame fusion is the most common and ine xpensive way to makesynthetic ruby, plus synthetic sapphire and synthetic spinel in man ycolors. These usually sell at retail for a few dollars per carat. They’rewidely used in class rings, imitation birthstone jewelry, and trendy fashionitems. Pulling is also low-cost. Every year the process produces millionsof carats of synthetic ruby, synthetic sapphire, and synthetic spinel.Pulling can produce very large crystals that are defect-free.These are often used to make lasers and semiconductors.

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Solution growth comes close to reproducing the conditions in which natural gems form. It requiressophisticated equipment and long periods of time – from se veral weeks for hydrothermal synthetics, tomore than a year for some flux products. Products created using solution-gro wing methods are thereforemore expensive than melt-grown synthetics.

Hydrothermal methods produce synthetic emerald, synthetic ruby, synthetic sapphire, and syntheticquartz (amethyst, citrine, and other colors). Flux gems include higher quality “luxury” synthetic ale xan-drite, synthetic emerald, synthetic ruby, and synthetic sapphire. These can retail for hundreds of dollars percarat. For this reason, they’re often marketed as “created” or “cultured” gems under manuf acturers’ brandnames. Chatham Created Emerald is one example.

The flux and hydrothermalprocesses more closely dupli-cate the processes of nature.The gems made by theseprocesses can cost hundredsof dollars per carat.

Photo courtesy Chatham CreatedGems.

• Solution-Grown Synthetics – Themain solution-growth techniques are classi-fied as flux or hydrothermal (HIGH-dro-THERM-al). Flux synthesis was developedin the 1930s. It involves dissolving ingredi-ents in a high-temperature chemical solu-tion, and then allowing them to cool andcrystallize. Hydrothermal processes werefirst used for commercial gem synthesis inthe 1960s. Ingredients are dissolved in amixture of water and chemicals at hightemperature and pressure. Under theseconditions, the synthetic material forms onseed plates that provide the pattern forcrystallization.

HydrothermalProcess.

Flux melt process.

Graphics courtesy MichaelO’Donoghue, A Guide to Man-madeGemstones.

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IMITATIONS There’s no way to know when humans first began

to produce imitations of the gems they loved. Morethan 6,000 years ago the Egyptians may ha ve usedpottery with a blue-green glaze to imitate turquoise. By1000 BC they were mimicking emerald and other gemswith glass. Ever since, imitations have had a place inthe gem world.

Today there’s healthy demand for imitations. Low-cost versions appeal to young people looking foraffordable beauty. They’re also favorites withcustomers accessorizing the season’s clothing styles.More expensive imitation-set pieces show up in manyhigh-fashion lines. This trend started with Coco Chanelin the 1920s, and it’s still going strong.

Imitation gemstones may or may not be part ofyour inventory. That decision depends on your store’smerchandising philosophy and target market. Even ifyou don’t sell imitations, however, you may encounterthem during take-in for repairs or appraisals. Youshould be prepared to discuss them with customers.

Natural gemstonescan imitate othernatural gems.Above, pink spineland on the right,pink sapphire.

Photos courtesy Tino Hammid.

Glass is among theoldest imitations.

To many customers the terms “synthetic” and “imitation” mean the samething. There are differences you may need to clarify, though. As you’velearned, a synthetic is a duplicate of its natural counterpart. An imitation (orsimulant) is only a look-alike. Appearance is all it has in common with thegem it imitates.

At the same time, imitations cut across other product boundaries. Theyinclude a wide assortment of natural and artif icial materials:

• Natural Imitations – It was once a common practice to sell somegems as substitutes for others simply because the y looked like them. (Forinstance, red garnet for ruby, or iolite for tanzanite.) Consumer interest inall kinds of gems has changed that, however. While you might suggestcolor alternatives, it’s usually best to present natural gems on their o wnmerits.

The designer Coco Chanelwas shrewd, chic and onthe cutting edge. She couldnot afford the fashions ofthe time so made up herown, including fake jewelry.

• Glass and Ceramics – These are amongthe oldest imitations, and they’re still the mostpopular. Glass can be produced in almost an ycolor and texture. Therefore it’s used for inex-pensive imitations of all kinds. Since mostceramics are opaque, they imitate gems likecoral, jade, lapis lazuli, and turquoise.

• Synthetic Look-Alikes – Next to glass,flame-fusion synthetic sapphire and syntheticspinel are the top transparent gemstone imitatorsin terms of volume. They’re available in manycolors. They cost more to produce than glass,but they also offer better wearability. Moreexpensive synthetics often marketed as imita-tions include synthetic cubic zirconia andsynthetic quartz.

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• Plastics – Most plastic imitations aren’t veryconvincing, so you’ll seldom see them in a f ine jewelrystore. Notable exceptions are plastic imitations ofcoral, ivory, and other gem materials that come fromthreatened or endangered species. You’ll learn moreabout these “environmentally friendly” alternatives inLesson 6.

In addition to these imitations, there are others that f itin the final category of this survey: assembled products.

Plastic is usually molded togem shapes. As a result,you can often see evidencelike concave facets.

Photo courtesy Jewelex.com

Synthetic alexandrite-like sapphire(a man-made corundum) is acommon imitation on the market.

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ASSEMBLED PRODUCTS Assembled products – or composites – are made

by fusing or bonding separate pieces of natural orman-made gemstones. Those with two main compo-nents are often called doublets. Those with threecomponents are known as triplets. Like treatments andglass imitations, assembled gemstones have a longhistory. They date back at least to the Roman Empire.Over the years there have been countless versions andvariations. The ones you might see in today’s market-place boil down to three main types:

• Assembled Imitations – These are usuallymade as low-cost look-alikes for natural gems withcolors that flame-fusion synthetic sapphire orsynthetic spinel can’t reproduce. An example is thesynthetic spinel triplet, which most often imitatesemerald. It consists of a layer of deep greencement or glass sandwiched between a top andbottom of colorless synthetic spinel.

With constructs, there’s not an attempt atimitating or disguising – just creatingimaginative combinations.

Photo by Robert Weldon courtesy Maxam Magnata.

An opal triplet has athin layer of opal with ablack backing (glass orchalcedony) and aquartz or glass dome.

An opal doublet consists of a thinlayer of opal on a stronger backing.

• Natural Remnants – The objective here is maximizing theuse of beautiful and valuable natural gem material. The bestexamples are opal doublets and triplets. The key ingredient inboth is a piece of gem-quality opal that’s too thin to be used byitself in jewelry. In a doublet, the opal sliver is cemented to abacking of stronger supporting material such as chalcedon y,glass, or plastic. (Using a black adhesive can heighten the play-of-color.) In a triplet, the opal and its backing are co vered witha protective top made from colorless quartz or glass.

• Creative Combinations – In the quest for new anddifferent effects, gemstone artists use a variety of materials inpieces sometimes called constructs. Very expensive gems areusually excluded, but almost anything else – natural or man-made – can show up in these creative productions. There’s noattempt at imitation or at disguising the nature of the product.Instead, there’s just a playful celebration of the beauty anddiversity that exist in the gem world.

Triplet

Doublet

A synthetic spinel tripletconsists of a layer ofcolored cement sand-wiched between twocolorless pieces ofsynthetic spinel.

ASSEMBLEDOPAL

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RECAP OF KEY POINTS

• The gem world includes minerals, organic materials, treated gems, synthetics,imitations, and assembled products. As a jewelry sales professional, it’s essen-tial for you to understand the distinctions between them.

• Most natural gems are minerals that were created by Earth’ s rock-formingprocesses. Minerals are classified into species based on the combination ofchemical composition and crystal structure. Varieties are subcategories withinspecies, usually distinguished by color or phenomenon. Groups are made upof closely related species.

• A treatment is an artificial process, other than fashioning, that improves agem’s appearance or durability. Treatments used on colored gemstones includebleaching, coating, diffusion, dyeing, filling, heating, impregnation, and irradi-ation. Commonly treated gems include amethyst, aquamarine, chalcedon y,citrine, coral, cultured pearls, emerald, jade, lapis lazuli, opal, ruby , sapphire,shell, smoky quartz, tanzanite, tiger’s-eye, topaz, turquoise, tourmaline, andzircon.

• Synthetics are man-made versions of natural gems. They have essentially thesame compositions, structures, and characteristics as their natural counterparts.Among those available in the jewelry industry are synthetic forms of alexan-drite, amethyst, citrine, emerald, opal, ruby, sapphire, smoky quartz, andspinel. Most of these can be divided into low-cost melt-grown products, andmore expensive solution-grown “luxury” synthetics.

• Imitations are look-alikes. They encompass a varied assortment of natural andartificial materials including natural simulants, glass and ceramics, lo w-costsynthetics, and plastics.

• Assembled products also serve as imitations, as well as pieces made to maxi-mize the use of natural gem material or to create inno vative color combina-tions.

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LESSON 3 FOLLOW-UP CHECKLIST

____ Develop short, simple introductions for the mineral gems you sell. Atthis point, just focus on saying enough to identify what you’ reshowing. To make sure you’re being clear, try out your introductionson family members or friends who aren’t in the jewelry business.

____ Review the lesson section on Treated Gems, and determine how manyof the colored gems you sell are on the “commonly treated” list. Thencheck the Treatment section for those gems in the Colored GemstoneCompendium. Talk to your coworkers and your store’s owner ormanager about how you might disclose treatment to customers.(Remember, however, that Lesson 15 will discuss this topic in detail.)

____ Look through your store displays and see how many imitations andsynthetics you can identify. With your manager or coworkers discusswhere imitation and synthetic gemstone jewelry fit in your store’sproduct lines. If you don’t sell them, discuss the reasons for thismarketing decision.

Lesson 3 Self-Test

This lesson also includes a Self-Test that’s designed to help you gauge your comprehension of the lesson material. The test is an important part of the learning process, so be sure to complete it.

When you're ready to take the test, go to the Course Materials page (the one that lists all the lessons) and click on "Take Self-Test." Make certain you select the test for this lesson.

All questions in the test are based on Lesson 3. More than one answer for a question might seem correct, but you should select the one best answer based on the lesson discussion.

As you take the test, you may refer to the lesson. To do this, you’ll need to have the lesson loaded in a separate window of your browser.

If you feel certain about a question, try answering it without looking at the lesson. But if you’re not sure, check the lesson before answering.

After you answer a question, you'll receive immediate results and feedback. You'll find out whether you answered correctly, what the correct answer was (in case you missed it), and also the page number in the lesson where the information can be found. Take time to review any material you're not completely clear on.

At the end of the test, you’ll receive your overall results. Then you’ll be able to continue to the next step in your coursework.

If you have questions or need help, please contact us. You can use this website – just click on Help. You can also email studenthelp@diamondcouncil.org or phone 615-385-5301 / toll free 877-283-5669.

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