Diamond Simulants PDF

DDG Ass 18 Diamond Simulants Diamond Simulants: -Simulants have been used in jewelry since the natural diamond rush in the late 1800s. - Simulants are both readily available and much cheaper then lab grown or natural diamonds - Simulants make fashionable jewelry available to people who want the look...

DDG Ass 18 Diamond Simulants Diamond Simulants: -Simulants have been used in jewelry since the natural diamond rush in the late 1800s. - Simulants are both readily available and much cheaper then lab grown or natural diamonds - Simulants make fashionable jewelry available to people who want the look of diamonds without the high price -Simulants don’t have any of diamond’s physical or chemical properties, and the properties they do have vary widely. Their only connection to diamonds is that they look like them - In fact, any colorless transparent material can be used as a diamond simulant. Simulants can be either natural or created by humans. - they can be manufactured in quantity and in nearly any size -100-plus years they have been used, from glass in the late 1700s to synthetic moissanite in the 1990s Attributes of Diamond Simulants: - A successful Simulant must mimic some of these features to be convincing simulants - no simulant can mimic all of the properties well. Popular Diamond Simulant: - Some of the oldest diamond simulants are no longer manufactured for jewelry use, but they still exist and you might find them at estate sales or when a repair comes in Glass and Foil Back - Glass was an effective diamond imitation beginning in the 1700s, when European glassmakers discovered that adding lead oxide to glass made it more dispersive and brilliant. - Other name for glass is “paste,” from the Italian word pasta. - Glass has much lower brilliance, luster, and hardness than diamond, so it’s fairly easy to recognize. It also has a lower refractive index (RI) - Stones backed with metal foil are called foilbacks. Not all foilbacks are simulants. - Before the 1700s, almost all transparent gems, including diamonds, were routinely backed with foil to provide color or improve brilliance. - A modern method for making foilbacks involves application of a mirroring film rather than metal foil. - Rhinestone is a common trade term for diamond imitations made of glass or plastic, foilbacked or not. - The word originally referred to simulants made from a colorless quartz from the Rhine River Valley Synthetic Sapphire and Synthetic Spinel : - In the late 1800s, French chemist Auguste Verneuil developed a process of synthetic crystal growth for commercial use. The process involved melting powdered materials over a flame and then cooling them until they crystallized. - Synthetic and natural colorless sapphire were popular diamond simulants in the 1990s. Zircon : - Zircon is a natural gem that occurs in a variety of colors. - Its colorless form was rare until the early 20th century, when heat-treating methods made it more common. - It’s more brilliant than glass and has medium fire, doubly refractive,show wear quickly, are brittle and chip and scratch easily - Some consumers may also say “zircon” when they actually mean cubic zirconia, cubic zirconia is a different diamond simulant. Synthetic Rutile : - Scientists searching for a better paint whitener discovered synthetic rutile by accident in 1948. (natural rutile is rarely used in jewelry) - Despite its yellowish bodycolor, synthetic rutile was briefly used as a diamond simulant. It’s no longer produced, but you might find it in some estate jewelry. - synthetic rutile is quite brilliant(strong fire) , highly doubly refractive, also has very high dispersion which is actually detract from its brilliance and can even make the stone look cloudy ans quickly wears Strontium Titanate: - Strontium titanate (a compound of the elements strontium and titanium) first appeared as a simulant in 1953. -Like diamond, strontium titanate is singly refractive. It’s closer to colorless noticeably more dispersive than diamond. It also has a low hardness, so it’s not very durable. YAG and GGG: - YAG was the first to be used as a diamond simulant. Aggressive promotion boosted YAG’s commercial success, such as its use for Cartier’s replica of the 69.42-ct. Taylor-Burton diamond. - It has good hardness (about 8.25 on the Mohs scale) and brilliance, YAG was the most popular diamond simulant for many years. -But it lacked the distinct fire of diamond, and as newer and better simulants appeared, YAG lost its popularity. -Although both yttrium aluminum garnet (YAG) and gadolinium gallium garnet (GGG) are lab-grown and have garnet-like structure, neither are synthetic garnets as they lack the chemistry of a natural garnet - GGG is a little more brilliant and dispersive than YAG. Its dispersion is almost the same as diamond’s, so it shows similar fire. GGG’s major drawback is its lower hardness. It scratches fairly easily. -GGG also has high SG (7.05), so it’s much heavier than a diamond of the same size, making its heft higher Synthetic Cubic Zirconia: - Synthetic cubic zirconia (CZ) is a modern simulant that entered the market in the early 1970s. - It has since become the most common diamond simulant. It’s called “synthetic” because it has an extremely rare natural counterpart. - CZ is almost as brilliant and lustrous as diamond, and it has slightly higher dispersion, appearance is fairly close to diamond’s, it is often used as a counterfeit. - CZ comes in a variety of different colors, so it is a convincing colored diamond simulant. However, most of CZ’s colors are quite saturated, while natural colored diamonds typically have less saturation. -CZ is the most popular diamond simulant, it’s a jewel in its own right. Synthetic Moissanite: - synthetic moissanite tends to be slightly yellowish or greenish, it is a convincing diamond simulant. -Slightly less brilliant than diamond, but it has more fire than diamond and CZ, it also has high luster. -Like CZ, it is marketed as a jewel in its own right, but it is more expensive to produce so is less common in the market than CZ -Moissanite gets its name from Dr. Henri Moissan, a Nobel Prize–winning chemist. -Synthetic moissanite is silicon carbide. It was first developed for industrial use, superior hardness—about 9.25 on the Mohs scale -Doubly refractive,SG (3.21) is lower than diamond’s aka low heft, -colored synthetic moissanite is not as common as colored CZ. -However, synthetic moissanite is routinely found in black to imitate black diamond, and is hard to identify Assembled Simulants: - An assembled simulant is made up of two or more components. Assembled diamond simulants are usually doublets, consisting of two different materials cemented or fused together. -One of the first types of assembled simulants used were garnet-and-glass doublets in the mid-1840s, doublets consisted of a reddish garnet top fused to a glass base. - quick detection of most garnet-and-glass doublets, rock the jewel back and forth under a light and notice the luster difference - Newer doublets have synthetic spinel or synthetic sapphire crowns and strontium titanate pavilions. Coated Simulants: - Coated simulants are relatively new to the market and have become more common since the early 2000s. -hese simulants are typically either CZ or synthetic moissanite with a coating that contains some form of synthetic diamond particles. -coatings are also too thin to be seen under standard magnification and less resistant to scratching than diamond, so they easily wear away,Simulants have also been coated to produce color. - attention to facet junctions for oily or iridescent-looking facets under different lighting. How to Detect a Simulant: - Some require instruments, and others are as simple as observing the diamond under different lighting and magnification - It is important to remember that all of these methods need to be used in combination Thermal Conductive Testing: - A gem’s thermal conductivity is the rate at which its surface temperature changes in response to a specific amount of heat - Diamond has higher thermal conductivity than almost any simulant. -Most thermal testers are operated by holding the tip of the tester’s probe against a facet. - The mounting, if you touched metals, the temperature of the room, and the size of the stone may also affect the results. - A black synthetic moissanite might indicate diamond on a thermal tester due to its high thermal conductivity. -Also look at the inclusions inside the stone. Moissanite and diamond have different inclusions Electrical Conductivity and Testing: - A moissanite tester checks electrical conductivity—how well an electrical current passes through a material - Synthetic moissanite can conduct electricity, but the majority of diamonds do not. -A moissanite tester passes a small electrical current through the stone, which travels to the metalwork and into your hand holding the mounting to your other arm and finger that press on the metal plate - Certain models of diamond/moissanite testers test for both thermal and electrical conductivity at the same time. They are called multi-testers Doubling: - First, look through the table of the stone at the pavilion facet junctions to see if there are one or two reflections -Some materials that have a less symmetrical crystal system, light splits into two beams. -You can observe this by viewing a stone in at least three directions under a loupe or microscope Dispersion: - A material’s dispersion is a measure of the difference between the refractive index of the red wavelength of light and the refractive index of the violet wavelength. -Diamond has moderate fire. Simulants can have less, similar, or more fire than diamonds due to differences in dispersion values. Read Through: - Diamond has a small critical angle, and if a cutter chooses the right proportions read through isn't possible -Many diamond simulants have lower RIs and larger critical angles than diamond. allowing read through -This test doesn’t work for fancy shapes because of their different proportions and faceting styles. Pavilion Flash: - Due to their chemistry other simulants have color flashes on their pavilion facets under darkfield lighting. -The pavilion color flash test works only for some simulants, but it works particularly well for CZ whose pavilion facets show a bright orange flash under darkfield lighting as you rock and tilt the stone. -The test is not accurate on fancy cuts, poorly proportioned stones, or stones with less than 50 percent orange flash on pavilion facets. -YAG can also show a pavilion flash: a violet and blue one. Specific Gravity and Heft: -Specific gravity is the ratio of the density of a substance to the density of an equal volume of water. - Most simulants have a much higher SG. The exception is synthetic moissanite, which has SG slightly lower than diamond’s. -Heft compares the size of an object to its weight and only works for loose stones -The CZ has higher heft. This is because CZ has an SG of 5.80–6.00. GGG has an SG of 7.00 and would feel extremely heavy for its size. Hardness, Luster and Polish Quality: - Diamond is not only harder than any other natural gem—it’s also a lot harder than any natural or manufactured simulant. -Diamond’s exceptional hardness makes very sharp facet junctions and superior polish possible. -A simulant’s comparative softness means that its facet junctions are more rounded than a diamond’s, with -Synthetic moissanite, at 9.25, are much sharper than in other simulants, but still rounded compared to diamond’s. - Simulants might show signs of wear easily, such as abrasions, scratches, or chips. -Diamond’s capacity for a superior polish gives it much higher luster—adamantine—than a simulant - Subadamantine and vitreous are the best lusters simulants can have. Girdle Appearance: - This test doesn’t help for modern simulants. The test is only useful for older simulants, such as those in estate jewelry. - In the 21st century, diamonds with polished or faceted girdles are more common. A polished or faceted girdle can slightly increase a diamond’s color grade. -In the 20th century, it was common to see diamonds with bruted girdles,something simulants nca't achieve do to there lower hardness Inclusions and Blemish: -Some inclusions and blemishes occur in natural diamonds but not lab-grown stones, which can help determine whether a stone is a diamond or a simulant - Twinning wisps, internal graining, and etch channels are inclusions that occur in natural diamonds but not in any synthetic diamond simulants. -Naturals are blemishes helpful in diamond identification. They contain growth marks such as trigons or parallel grooves. - As most diamonds contain inclusions, this can aid in their identification, except higher-clarity diamonds, or those that only have feathers, cavities, or chips, indenticating further tests are needed. -Mineral inclusions can also be helpful like crystals or needles, however you still need to confirm that it isn't another natural colorless stone (topaz, sapphire, etc) - Gas bubble inclusions can sometimes occur in human-made simulants, such as CZ, YAG, GGG, synthetic sapphire, glass, synthetic spinel, synthetic rutile, and strontium titanate. - most human-made simulants are eye-clean and don’t contain many inclusions Dealing in Simulants: - People with limited budgets are more likely to visit a jewelry store if they know they’ll find something beautiful at a price they can afford -The best simulants usually have high-quality settings. -The right attitude on a jewelry professional’s part will help clients or customers feel good about buying simulants, bring them back for diamonds when they can afford them. Simulant Names: - Diamond simulant manufacturers have given their products trade names, Some of them are as fanciful as “Rainbow Magic Diamond” for synthetic rutile and “Diamontina” for strontium titanate. -Because synthetic cubic zirconia is popular and heavily promoted—Some of those names are Absolute, Diamanti LUXE, Diamonair, Diamonesk, Diamonesque, and Diamonique III. -Many stores promote "Diamond hybrids"or "Hybrid diamond", and each retailer has their own patent, but usually the stone consists of a simulant, most likely a CZ, with a coating of diamond particles. -“Diamond hybrid” may also be used as a name for certain assembled simulants. -Misnomers used in the past for some simulants include “Matura diamonds” & “Herkimer diamonds.” These are actually colorless zircon and a type of colorless quartz. Mistakes and Deceptions: -If you can’t positively identify the material in a piece of jewelry when you accept it from a customer for repair or cleaning, use a neutral description. EX: Words like “near-colorless emerald cut” are best on a take- in form. -You should never sell a gem—wholesale or retail—without knowing exactly what it is. False Adversing -Promotions for diamond simulants are sometimes full of false or exaggerated claims. -The best way to avoid becoming part of the problem—and to impress clients or customers with honesty and expertise—is to arm yourself with the facts. Stay Alert: - The ability to remain objective and rational is tested every time you accept jewelry or diamonds from someone - Note that it may be easier for a con artist to trick a salesperson eager to make a big sale or get a great deal. -Wholesalers must be watchful for simulants hidden in parcels of rough or finished diamonds. -Stay Current with knowledgeable and skills can help you identify new tricks