What is cz made out of?
Cubic zirconia (abbreviated CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO4). It is sometimes erroneously called cubic zirconium.
Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained the most gemologically and economically important competitor for diamonds since commercial production began in 1976. Its main competitor as a synthetic gemstone is a more recently cultivated material, synthetic moissanite.
Cubic zirconia is crystallographically isometric, an important attribute of a would-be diamond simulant. During synthesis zirconium oxide naturally forms monoclinic crystals, which are stable form under normal atmospheric conditions. A stabilizer is required for cubic crystals (taking on the fluorite structure) to form, and remain stable at ordinary temperatures; typically this is either yttrium or calcium oxide, the amount of stabilizer used depending on the many recipes of individual manufacturers. Therefore, the physical and optical properties of synthesized CZ vary, all values being ranges.
It is a dense substance, with a density between 5.6 and 6.0 g/cm3—about 1.65 times that of diamond. Cubic zirconia is relatively hard, 8–8.5 on the Mohs scale—slightly harder than most semi-precious natural gems.[1] Its refractive index is high at 2.15–2.18 (compared to 2.42 for diamonds) and its luster is vitreous. Its dispersion is very high at 0.058–0.066, exceeding that of diamond (0.044). Cubic zirconia has no cleavage and exhibits a conchoidal fracture. Because of its high hardness, it is generally considered brittle.
Under shortwave UV cubic zirconia typically fluoresces a yellow, greenish yellow or "beige". Under longwave UV the effect is greatly diminished, with a whitish glow sometimes being seen. Colored stones may show a strong, complex rare earth absorption spectrum.
Discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide.[2]
The high melting point of zirconia (2750 °C or 4976 °F) hinders controlled growth of single crystals. However, stabilization of cubic zirconium oxide had been realized early on, with the synthetic product stabilized zirconia introduced in 1929. Although cubic, it was in the form of a polycrystalline ceramic: it was used as a refractory material, highly resistant to chemical and thermal attack (up to 2540 °C or 4604 °F).[3]
In 1937, German mineralogists M. V. Stackelberg and K. Chudoba discovered naturally occurring cubic zirconia in the form of microscopic grains included in metamict zircon. This was thought to be a byproduct of the metamictization process, but the two scientists did not think the mineral important enough to give it a formal name. The discovery was confirmed through X-ray diffraction, proving the existence of a natural counterpart to the synthetic product.[4][5]
As with the majority of grown diamond substitutes, the idea of producing single-crystal cubic zirconia arose in the minds of scientists seeking a new and versatile material for use in lasers and other optical applications. Its production eventually exceeded that of earlier synthetics, such as synthetic strontium titanate, synthetic rutile, YAG (yttrium aluminium garnet) and GGG (gadolinium gallium garnet).
Some of the earliest research into controlled single-crystal growth of cubic zirconia occurred in 1960s France, much work being done by Y. Roulin and R. Collongues. This technique involved molten zirconia being contained within a thin shell of still-solid zirconia, with crystal growth from the melt. The process was named cold crucible, an allusion to the system of water cooling used. Though promising, these attempts yielded only small crystals.
Later, Soviet scientists under V. V. Osiko in the Laser Equipment Laboratory at the Lebedev Physical Institute in Moscow perfected the technique, which was then named skull crucible (an allusion either to the shape of the water-cooled container or to the form of crystals sometimes grown). They named the jewel Fianit after the institute's name FIAN (Physical Institute of the Academy of Science), but the name was not used outside of the USSR.[citation needed] This was known at the time as the Institute of Physics at the Russian Academy of Science.[6] Their breakthrough was published in 1973, and commercial production began in 1976.[7] In 1977 cubic zirconia began to be mass-produced in the jewelry marketplace by the Ceres Corporation with crystals stabilized with 94% yttria. Other major producers as of 1993 include Taiwan Crystal Company Ltd, Swarovski and ICT inc.[8][5] By 1980 annual global production had reached 60 million carats (12 tonnes) and continued to increase with production reaching around 400 tonnes per year in 1998.[8]
Because the natural form of cubic zirconia is so rare, all cubic zirconia used in jewelry has been synthesized, or created by humans.
Currently the primary method of cubic zirconia synthesis employed by producers remains to be through the skull-melting method. This method was patented by Josep F. Wenckus and coworkers in 1997. This is largely due to the process allowing for temperatures of over 3000 degrees to be achieved, lack of contact between crucible and material as well as the freedom to choose any gas atmosphere. Primary downsides to this method include the inability to predict the size of the crystals produced and it is impossible to control the crystallization process through temperature changes.[3][9]
The apparatus used in this process consists of a cup-shaped crucible surrounded by radio-frequency (RF) activated copper coils and a water-cooling system.[3][10]
Zirconium dioxide thoroughly mixed with a stabilizer (normally 10% yttrium oxide) is fed into a cold crucible. Metallic chips of either zirconium or the stabilizer are introduced into the powder mix in a compact pile manner. The RF generator is switched on and the metallic chips quickly start heating up and readily oxidize into more zirconia. Consequently, the surrounding powder heats up by thermal conduction and begins melting, which in turn becomes electroconductive and thus it begins to heat up via the RF generator as well. This continues until the entire product is molten. Due to the cooling system surrounding the crucible, a thin shell of sintered solid material is formed. This causes the molten zirconia to remain contained within its own powder which prevents it from contamination from the crucible and reduces heat loss. The melt is left at high temperatures for some hours to ensure homogeneity and ensure all impurities have evaporated. Finally, the entire crucible is slowly removed from the RF coils to reduce the heating and let it slowly cool down (from bottom to top). The rate at which the crucible is removed from the RF coils is chosen as a function of the stability of crystallization dictated by the phase transition diagram. This provokes the crystallization process to begin and useful crystals begin to form. Once the crucible has been completely cooled to room temperature, the resulting crystals are multiple elongated-crystalline blocks.[9][10]
The reason behind this shape is dictated by a concept known as crystal degeneration according to Tiller. The size and diameter of the obtained crystals is a function of the cross-sectional area of the crucible, volume of the melt and composition of the melt.[3] The diameter of the crystals is heavily influenced by the concentration of Y2O3 stabilizer.
When observing the phase diagram the cubic phase will crystallize first as the solution is cooled down no matter the concentration of Y2O3. If the concentration of Y2O3 is not high enough the cubic structure will start to break down into the tetragonal state which will then break down into a monoclinic phase. If the concentration of Y2O3 is between 2.5-5% the resulting product will be PSZ (partially stabilized zirconia) while monophasic cubic crystals will form from around 8-40%. Below 14% at low growth rates tend to be opaque indicating partial phase separation in the solid solution (likely due to diffusion in the crystals remaining in the high temperature region for a longer time). Above this threshold crystals tend to remain clear at reasonable growth rates and maintains good annealing conditions.[9]
Because of cubic zirconia's isomorphic capacity it can be doped with several elements to change the color of the crystal. A list of specific dopants and colors produced by their addition can be seen below.
The vast majority of YCZ (yttrium bearing cubic zirconia) crystals clear with high optical perfection and with gradients of the refractive index lower than 5 × 10 − 5 {\displaystyle 5\times 10^{-5}} .[9] However some samples contain defects with the most characteristic and common ones listed below.
Due to its optical properties yttrium cubic zirconia (YCZ) has been used for windows, lenses, prisms, filters and laser elements. Particularly in the chemical industry it is used as window material for the monitoring of corrosive liquids due to its chemical stability and mechanical toughness. YCZ has also been used as a substrate for semiconductor and superconductor films in similar industries.[9]
Mechanical properties of partially stabilized zirconia (high hardness and shock resistance, low friction coefficient, high chemical and thermal resistance as well as high wear and tear resistance) allow it to be used as a very particular building material, especially in the bio-engineering industry: It has been used to make reliable super-sharp medical scalpels for doctors that are compatible with bio-tissues and contain an edge much smoother than one made of steel.[9]
In recent years[when?] manufacturers have sought ways of distinguishing their product by supposedly "improving" cubic zirconia. Coating finished cubic zirconia with a film of diamond-like carbon (DLC) is one such innovation, a process using chemical vapor deposition. The resulting material is purportedly harder, more lustrous and more like diamond overall. The coating is thought to quench the excess fire of cubic zirconia, while improving its refractive index, thus making it appear more like diamond. Additionally, because of the high percentage of diamond bonds in the amorphous diamond coating, the finished simulant will show a positive diamond signature in Raman spectra.
Another technique first applied to quartz and topaz has also been adapted to cubic zirconia: An iridescent effect created by vacuum-sputtering onto finished stones an extremely thin layer of a precious metal (typically gold), or certain metal oxides, metal nitrides, or other coatings.[11] This material is marketed as "mystic" by many dealers. Unlike diamond-like carbon and other hard synthetic ceramic coatings, the iridescent effect made with precious metal coatings is not durable, due to their extremely low hardness and poor abrasion wear properties, compared to the remarkably durable cubic zirconia substrate.
There are a few key features of cubic zirconia which distinguish it from diamond:
Cubic zirconia, as a diamond simulant and jewel competitor, can potentially reduce demand for conflict diamonds, and impact the controversy surrounding the rarity and value of diamonds.[12][13]
Regarding value, the paradigm that diamonds are costly due to their rarity and visual beauty has been replaced by an artificial rarity[12][13] attributed to price-fixing practices of De Beers Company which held a monopoly on the market from the 1870s to early 2000s.[12][14] The company pleaded guilty to these charges in an Ohio court in 13 July 2004.[14] However, while De Beers has less market power, the price of diamonds continues to increase due to the demand in emerging markets such as India and China.[12] The emergence of artificial stones such as cubic zirconia with optic properties similar to diamonds, could be an alternative for jewelry buyers given their lower price and noncontroversial history.
An issue closely related to monopoly is the emergence of conflict diamonds. The Kimberley Process (KP) was established to deter the illicit trade of diamonds that fund civil wars in Angola and Sierra Leone.[15] However, the KP is not as effective in decreasing the number of conflict diamonds reaching the European and American markets. Its definition does not include forced labor conditions or human right violations.[15][16] A 2015 study from the Enough Project, showed that groups in the Central African Republic have reaped between US$3 million and US$6 million annually from conflict diamonds.[17] UN reports show that more than US$24 million in conflict diamonds have been smuggled since the establishment of the KP.[18] Diamond simulants have become an alternative to boycott the funding of unethical practices.[17] Terms such as “Eco-friendly Jewelry” define them as conflict free origin and environmentally sustainable.[19] However, concerns from mining countries such as the Democratic Republic of Congo are that a boycott in purchases of diamonds would only worsen their economy. According to the Ministry of Mines in Congo, 10% of its population relies on the income from diamonds.[15] Therefore, cubic zirconia are a short term alternative to reduce conflict but a long term solution would be to establish a more rigorous system of identifying the origin of these stones.
Cubic zirconia is classified as a diamond simulant - a stone that looks similar to natural diamonds, but is made of different material. Natural and lab-grown diamonds are made of carbon, while cubic zirconia is made of zirconium dioxide (ZrO2). The cubic part of the name comes from the fact that the stone has a cubic crystalline form. Diamonds also have a cubic crystalline form, so cubic zirconia is a great diamond lookalike.
The material was originally used by scientists experimenting with different synthetic materials to use in lasers. In the 1970s, scientists in Russia perfected the technique of growing single cubic zirconia crystals. The clear, sparkly crystals were used to make mass-produced jewelry. Today cubic zirconia crystals are a popular diamond dupe in necklaces, earrings, bracelets and rings of all kinds.
How does cubic zirconia stack up against diamond? Let's compare a few of the key characteristics.
Like diamond, cubic zirconia is naturally colorless. In fact, most natural diamonds have a faint yellow or brown tint. Cubic zirconia is completely clear, comparable to a D color rating. Under natural light, diamonds give off white light. Cubic zirconia will show more fire. Both effects are beautiful and depend on personal preference. If you're looking for that telltale diamond sparkle, however, you won't find it in a cubic zirconia stone.
Cubic zirconia can also be color treated with different elements, resulting in a rainbow of hues. There are even multi-colored cubic zirconia stones, if you want a truly one-of-a-kind look. These stones are affordable and unique alternatives to fancy colored diamonds or colored gemstones like emerald, ruby and sapphire.
Natural diamonds (and even lab-grown diamonds) have flaws — tiny imperfections within the stone called inclusions. Cubic zirconia has no natural internal flaws but it can show telltale signs of its own lab-grown origins, such as tiny gas bubbles that contain unmelted zirconium dioxide powder used in its creation. Cubic zirconia stones are cut and polished after they're made. They can be cut into many common diamond shapes, like round, princess, pear and cushion.
When looking for an engagement ring, it can be tempting to choose a cubic zirconia stone simply based on price. Cubic zirconia rings are far cheaper than diamond rings and at first glance, they look the same. This beauty won't last though-cubic zirconia only lasts about two years before its beauty fades. Natural diamonds and other gemstones are expensive, but will last a lifetime.
Diamonds are well-known for their hardness, which ranks at 10 on Mohs hardness scale. Diamonds are very durable and won't scratch from daily use. Cubic zirconia is an 8.5 on the hardness scale. It doesn't seem like a huge difference, but it is. Cubic zirconia scratches easily from daily use-even household dust can scratch the stones. Cubic zirconia also absorbs oils from skin and everyday products. After a few years, even the shiniest cubic zirconia will have a cloudy, scratched appearance. This is not a huge deal if you want to replace your ring every few years, but it is important to consider when comparing cubic zirconia to diamond.
Cubic zirconia is very inexpensive, since it's synthetic and mass-produced. A cut and polished one carat cubic zirconia stone will cost $20 and a similar two carat stone will cost about $30. This is far cheaper than diamonds, which start at $1800 for one carat and increase considerably as size goes up.
Cubic zirconia engagement rings range in price, largely depending on the metal the setting is made of. Rings in the $20-$40 price range are typically made of brass, silver, or copper plated with gold or platinum. The plating on these rings will typically wear away quickly, so it's smart to avoid them. Similarly, many websites sell cubic zirconia engagement rings that cost $100 or more. These rings have bands made from finer metals like 14K gold or platinum. Cubic zirconia stones scratch and fade very easily, losing their luster after about two years. It's not worth spending the extra money for a nicer band when you'll end up replacing the entire ring anyway.
Sterling silver or stainless steel are good metals to pair with cubic zirconia. These rings range from $50-$90. With sterling silver or stainless steel, you won't have to worry about plating chipping off, and you won't be overpaying for the setting.
Another thing to watch for is cubic zirconia rating. Some retailers assign grades, like A, 1A, AAA, AAAAA or 5A, to their cubic zirconia stones. According to retailers, grade AAAAA cubic zirconia stones are the highest quality and grade A are the lowest. However, these grades have no standard across retailers and there are no policies to ensure quality. Cubic zirconia is man-made and mass produced, so the quality between stones is consistent. The cubic zirconia grading system is essentially a marketing tactic with no science behind it, so don't overpay for a supposedly high-quality cubic zirconia stone.
Everyone has their own personal preference when it comes to engagement rings. Cubic zirconia is the best option if you're on a very strict budget. Look for stainless steel or sterling silver cubic zirconia engagement rings. These are beautiful, but inexpensive, and both the band and the stone will last a few years.
A cubic zirconia engagement ring is also a good option if you think your taste will change over time. Diamonds last forever and it can be a daunting task to pick out a stone and setting you'll want for years! Cubic zirconia rings are very inexpensive, so you can choose one and wear it for a while to see if you like it.
Cubic zirconia is also a popular choice for travel rings. If you have a diamond engagement ring and want to leave it at home while you're on vacation, at the beach or pool, or doing outdoor activities like hiking or skiing, consider a cubic zirconia ring. No one will be able to tell the difference! You won't have to worry about your real ring getting damaged, lost, or stolen.
Cubic zirconia is a manmade mineral made of zirconium dioxide. CZs can appear to be very like diamonds, but they have very different mineral structures. Cubic zirconias have been found in nature in small amounts, but the vast majority used in the jewelry are man-made in a lab.
Cubic zirconia (abbreviated CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO4). It is sometimes erroneously called cubic zirconium.
Because of its low cost, durability, and close visual likeness to diamond, synthetic cubic zirconia has remained the most gemologically and economically important competitor for diamonds since commercial production began in 1976. Its main competitor as a synthetic gemstone is a more recently cultivated material, synthetic moissanite.
Cubic zirconia is crystallographically isometric, an important attribute of a would-be diamond simulant. During synthesis zirconium oxide naturally forms monoclinic crystals, which are stable form under normal atmospheric conditions. A stabilizer is required for cubic crystals (taking on the fluorite structure) to form, and remain stable at ordinary temperatures; typically this is either yttrium or calcium oxide, the amount of stabilizer used depending on the many recipes of individual manufacturers. Therefore, the physical and optical properties of synthesized CZ vary, all values being ranges.
It is a dense substance, with a density between 5.6 and 6.0 g/cm3—about 1.65 times that of diamond. Cubic zirconia is relatively hard, 8–8.5 on the Mohs scale—slightly harder than most semi-precious natural gems.[1] Its refractive index is high at 2.15–2.18 (compared to 2.42 for diamonds) and its luster is vitreous. Its dispersion is very high at 0.058–0.066, exceeding that of diamond (0.044). Cubic zirconia has no cleavage and exhibits a conchoidal fracture. Because of its high hardness, it is generally considered brittle.
Under shortwave UV cubic zirconia typically fluoresces a yellow, greenish yellow or "beige". Under longwave UV the effect is greatly diminished, with a whitish glow sometimes being seen. Colored stones may show a strong, complex rare earth absorption spectrum.
Discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide.[2]
The high melting point of zirconia (2750 °C or 4976 °F) hinders controlled growth of single crystals. However, stabilization of cubic zirconium oxide had been realized early on, with the synthetic product stabilized zirconia introduced in 1929. Although cubic, it was in the form of a polycrystalline ceramic: it was used as a refractory material, highly resistant to chemical and thermal attack (up to 2540 °C or 4604 °F).[3]
In 1937, German mineralogists M. V. Stackelberg and K. Chudoba discovered naturally occurring cubic zirconia in the form of microscopic grains included in metamict zircon. This was thought to be a byproduct of the metamictization process, but the two scientists did not think the mineral important enough to give it a formal name. The discovery was confirmed through X-ray diffraction, proving the existence of a natural counterpart to the synthetic product.[4][5]
As with the majority of grown diamond substitutes, the idea of producing single-crystal cubic zirconia arose in the minds of scientists seeking a new and versatile material for use in lasers and other optical applications. Its production eventually exceeded that of earlier synthetics, such as synthetic strontium titanate, synthetic rutile, YAG (yttrium aluminium garnet) and GGG (gadolinium gallium garnet).
Some of the earliest research into controlled single-crystal growth of cubic zirconia occurred in 1960s France, much work being done by Y. Roulin and R. Collongues. This technique involved molten zirconia being contained within a thin shell of still-solid zirconia, with crystal growth from the melt. The process was named cold crucible, an allusion to the system of water cooling used. Though promising, these attempts yielded only small crystals.
Later, Soviet scientists under V. V. Osiko in the Laser Equipment Laboratory at the Lebedev Physical Institute in Moscow perfected the technique, which was then named skull crucible (an allusion either to the shape of the water-cooled container or to the form of crystals sometimes grown). They named the jewel Fianit after the institute's name FIAN (Physical Institute of the Academy of Science), but the name was not used outside of the USSR.[citation needed] This was known at the time as the Institute of Physics at the Russian Academy of Science.[6] Their breakthrough was published in 1973, and commercial production began in 1976.[7] In 1977 cubic zirconia began to be mass-produced in the jewelry marketplace by the Ceres Corporation with crystals stabilized with 94% yttria. Other major producers as of 1993 include Taiwan Crystal Company Ltd, Swarovski and ICT inc.[8][5] By 1980 annual global production had reached 60 million carats (12 tonnes) and continued to increase with production reaching around 400 tonnes per year in 1998.[8]
Because the natural form of cubic zirconia is so rare, all cubic zirconia used in jewelry has been synthesized, or created by humans.
Currently the primary method of cubic zirconia synthesis employed by producers remains to be through the skull-melting method. This method was patented by Josep F. Wenckus and coworkers in 1997. This is largely due to the process allowing for temperatures of over 3000 degrees to be achieved, lack of contact between crucible and material as well as the freedom to choose any gas atmosphere. Primary downsides to this method include the inability to predict the size of the crystals produced and it is impossible to control the crystallization process through temperature changes.[3][9]
The apparatus used in this process consists of a cup-shaped crucible surrounded by radio-frequency (RF) activated copper coils and a water-cooling system.[3][10]
Zirconium dioxide thoroughly mixed with a stabilizer (normally 10% yttrium oxide) is fed into a cold crucible. Metallic chips of either zirconium or the stabilizer are introduced into the powder mix in a compact pile manner. The RF generator is switched on and the metallic chips quickly start heating up and readily oxidize into more zirconia. Consequently, the surrounding powder heats up by thermal conduction and begins melting, which in turn becomes electroconductive and thus it begins to heat up via the RF generator as well. This continues until the entire product is molten. Due to the cooling system surrounding the crucible, a thin shell of sintered solid material is formed. This causes the molten zirconia to remain contained within its own powder which prevents it from contamination from the crucible and reduces heat loss. The melt is left at high temperatures for some hours to ensure homogeneity and ensure all impurities have evaporated. Finally, the entire crucible is slowly removed from the RF coils to reduce the heating and let it slowly cool down (from bottom to top). The rate at which the crucible is removed from the RF coils is chosen as a function of the stability of crystallization dictated by the phase transition diagram. This provokes the crystallization process to begin and useful crystals begin to form. Once the crucible has been completely cooled to room temperature, the resulting crystals are multiple elongated-crystalline blocks.[9][10]
The reason behind this shape is dictated by a concept known as crystal degeneration according to Tiller. The size and diameter of the obtained crystals is a function of the cross-sectional area of the crucible, volume of the melt and composition of the melt.[3] The diameter of the crystals is heavily influenced by the concentration of Y2O3 stabilizer.
When observing the phase diagram the cubic phase will crystallize first as the solution is cooled down no matter the concentration of Y2O3. If the concentration of Y2O3 is not high enough the cubic structure will start to break down into the tetragonal state which will then break down into a monoclinic phase. If the concentration of Y2O3 is between 2.5-5% the resulting product will be PSZ (partially stabilized zirconia) while monophasic cubic crystals will form from around 8-40%. Below 14% at low growth rates tend to be opaque indicating partial phase separation in the solid solution (likely due to diffusion in the crystals remaining in the high temperature region for a longer time). Above this threshold crystals tend to remain clear at reasonable growth rates and maintains good annealing conditions.[9]
Because of cubic zirconia's isomorphic capacity it can be doped with several elements to change the color of the crystal. A list of specific dopants and colors produced by their addition can be seen below.
The vast majority of YCZ (yttrium bearing cubic zirconia) crystals clear with high optical perfection and with gradients of the refractive index lower than 5 × 10 − 5 {\displaystyle 5\times 10^{-5}} .[9] However some samples contain defects with the most characteristic and common ones listed below.
Due to its optical properties yttrium cubic zirconia (YCZ) has been used for windows, lenses, prisms, filters and laser elements. Particularly in the chemical industry it is used as window material for the monitoring of corrosive liquids due to its chemical stability and mechanical toughness. YCZ has also been used as a substrate for semiconductor and superconductor films in similar industries.[9]
Mechanical properties of partially stabilized zirconia (high hardness and shock resistance, low friction coefficient, high chemical and thermal resistance as well as high wear and tear resistance) allow it to be used as a very particular building material, especially in the bio-engineering industry: It has been used to make reliable super-sharp medical scalpels for doctors that are compatible with bio-tissues and contain an edge much smoother than one made of steel.[9]
In recent years[when?] manufacturers have sought ways of distinguishing their product by supposedly "improving" cubic zirconia. Coating finished cubic zirconia with a film of diamond-like carbon (DLC) is one such innovation, a process using chemical vapor deposition. The resulting material is purportedly harder, more lustrous and more like diamond overall. The coating is thought to quench the excess fire of cubic zirconia, while improving its refractive index, thus making it appear more like diamond. Additionally, because of the high percentage of diamond bonds in the amorphous diamond coating, the finished simulant will show a positive diamond signature in Raman spectra.
Another technique first applied to quartz and topaz has also been adapted to cubic zirconia: An iridescent effect created by vacuum-sputtering onto finished stones an extremely thin layer of a precious metal (typically gold), or certain metal oxides, metal nitrides, or other coatings.[11] This material is marketed as "mystic" by many dealers. Unlike diamond-like carbon and other hard synthetic ceramic coatings, the iridescent effect made with precious metal coatings is not durable, due to their extremely low hardness and poor abrasion wear properties, compared to the remarkably durable cubic zirconia substrate.
There are a few key features of cubic zirconia which distinguish it from diamond:
Cubic zirconia, as a diamond simulant and jewel competitor, can potentially reduce demand for conflict diamonds, and impact the controversy surrounding the rarity and value of diamonds.[12][13]
Regarding value, the paradigm that diamonds are costly due to their rarity and visual beauty has been replaced by an artificial rarity[12][13] attributed to price-fixing practices of De Beers Company which held a monopoly on the market from the 1870s to early 2000s.[12][14] The company pleaded guilty to these charges in an Ohio court in 13 July 2004.[14] However, while De Beers has less market power, the price of diamonds continues to increase due to the demand in emerging markets such as India and China.[12] The emergence of artificial stones such as cubic zirconia with optic properties similar to diamonds, could be an alternative for jewelry buyers given their lower price and noncontroversial history.
An issue closely related to monopoly is the emergence of conflict diamonds. The Kimberley Process (KP) was established to deter the illicit trade of diamonds that fund civil wars in Angola and Sierra Leone.[15] However, the KP is not as effective in decreasing the number of conflict diamonds reaching the European and American markets. Its definition does not include forced labor conditions or human right violations.[15][16] A 2015 study from the Enough Project, showed that groups in the Central African Republic have reaped between US$3 million and US$6 million annually from conflict diamonds.[17] UN reports show that more than US$24 million in conflict diamonds have been smuggled since the establishment of the KP.[18] Diamond simulants have become an alternative to boycott the funding of unethical practices.[17] Terms such as “Eco-friendly Jewelry” define them as conflict free origin and environmentally sustainable.[19] However, concerns from mining countries such as the Democratic Republic of Congo are that a boycott in purchases of diamonds would only worsen their economy. According to the Ministry of Mines in Congo, 10% of its population relies on the income from diamonds.[15] Therefore, cubic zirconia are a short term alternative to reduce conflict but a long term solution would be to establish a more rigorous system of identifying the origin of these stones.
Learn more about the characteristics of diamonds and how to tell the difference between common imitation stones, like cubic zirconia, and natural diamonds.
The simplest way to tell if a gem is cubic zirconia or a real diamond is to inspect the stone for wear and color. Since diamonds are harder than almost any other substance, diamond will not scratch or wear down – in fact, they will scratch other surfaces.
If you have a microscope or magnifying glass, look at the very edges of the facets of the stone. A diamond's facet edges will usually look incredibly sharp and precise. If the stone looks abraded or worn down it is likely not a genuine diamond.
You should also look at the color of the light as it enters and escapes the surface of the stone. If you turn both a diamond and a CZ upside down, the bottom of a diamond will give off the entire rainbow of color reflections, whereas CZs usually have more exclusively orange and blue flashes. This is because cubic zirconias and diamonds have different refractive indexes.
These are the easiest ways to test whether a diamond is genuine or it’s cubic zirconia. There are more in-depth methods as well. We cover these comparisons in more detail below.
Simon G. accent stones are always genuine diamonds or colored gems. Shop our Designer Jewelry Showcase to find handcrafted diamond jewelry pieces.
Cubic zirconia is a manmade mineral made of zirconium dioxide. CZs can appear to be very like diamonds, but they have very different mineral structures. Cubic zirconias have been found in nature in small amounts, but the vast majority used in the jewelry are man-made in a lab. Synthetic diamonds are also made in labs, but they have the same carbon structure as diamonds – cubic zirconias do not.
A cubic zirconia is a real cubic zirconia, but it is not a real diamond. However, there are a few types of stones that are used as diamond simulants, and cubic zirconia is by far the most common and the most realistic.
In fact, Simon G. engagement rings feature cubic zirconia center stones. By using cubic zirconia, our customers have more control over the shape, style, and cost of their engagement ring. Some of our customers even decide to keep the CZ center stone until a later date, offering them greater budget flexibility.
Below we provide a more detailed overview of the key differences between diamond and CZ stones. From appearance to cost, there are a number of ways to tell if a diamond is real or an imitation.
While many people incorrectly think a diamond should have a clear appearance throughout, gemologists understand that a “white” diamond can still have a yellow, gray, or brown tint. This is the backbone of the D-Z color scale. For example, an M color white diamond would be slightly more yellow than a F color diamond.
Cubic zirconia is more likely to be completely colorless which is a tell-tale sign it isn’t a diamond. Another notable difference is that a diamond will have natural inclusions throughout the stone which is a sure sign it is real. However, inclusions can usually only be viewed under a microscope, so it’s hard to use them as an at-home method of testing a diamond's authenticity.
While these stones may look somewhat similar, their composition is very different. A diamond is the hardest stone known to man while a cubic zirconia has a much lower rating of hardness.
This is because diamonds are made of compressed carbon atoms, which lends to their brilliance and their remarkable hardness. Various hardness comparisons can be made to test whether a diamond is really a diamond, or if it’s actually CZ.
You can also test diamonds by checking the stone’s weight. A diamond and a cubic zirconia can be the same in actual size, but on a molecular level, zirconium dioxide is slightly denser than carbon. As a result, a CZ stone will weigh more than a diamond of the same exact size.
While diamonds come in varying prices due to the size or other factors determining the quality of a jewel, they will almost always cost more than a cubic zirconia.
If a piece of diamond jewelry seems too low for what you are getting, ask to see the certificates to ensure it is a real diamond and not a fake stone or synthetic being passed as the real thing. Of course, the best way to avoid any pitfalls is to shop with a reputable jeweler.
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