How to recognize natural sapphire. How to distinguish synthetic sapphire from real one
Sapphire is the second hardest mineral in the world and one of the most popular gemstones for jewelry. Many people think that sapphire is a deep blue color, although in fact these stones come in a variety of colors, including yellow, pink and orange.
Enjoy the beauty of this magnificent stone or give jewelry with it to people born in September, but first make sure that you really bought the sapphire. A lot can give away a fake: appearance, frame and other eloquent signs.
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Certificate of Authenticity
Ask the seller to show the certificate of authenticity, which is what all legally sold gemstones typically receive. Blue sapphires most often come to market from Australia and Thailand. Other sought-after crystals are mined in Kashmir, Ceylon and Burma. If they cannot provide you with any certificate or it indicates any other country other than those listed above, this is a reason to be wary. The document must describe the main characteristics: clarity, color, carat weight, size.
Color
Check the color in good lighting. Blue sapphire has a clear blue color. Beware of unnaturally colored stones. Remember that this is a naturally occurring mineral.
Size
One of the main reasons for the popularity and high cost of sapphires is their rarity. Therefore, a large discount on a fairly large gemstone should raise suspicions. When an offer seems too good to be true, there's a good chance it is. When cutting natural stones, the main goal is to preserve as much carat weight as possible. Therefore, stones with the correct geometric dimensions are extremely rare. Synthetic inserts, on the contrary, are made according to an exact standard (2; 3; 4; 5 mm). This is done for ease of setting during mass production of budget jewelry.
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Purity
Use a jeweler's loupe or microscope to evaluate cleanliness. Absolutely pure, transparent stones are extremely rare in nature. The presence of dark inclusions and defects in the form of small cracks is a clear sign of naturalness. Synthetic counterfeits are distinguished by high levels of purity and uniform color.
Surface
Check the surface for small scratches. Sapphire is an extremely durable mineral. Natural glass should not have any surface scratches, but on fairly soft glass they appear easily.
Cut
Frame
Check the setting of the stone as well. If the setting completely covers the edges or back of the sapphire, it is possible that this was done to hide defects in the sapphire or signs of a fake stone. The fastening quality is high, the insert stands evenly and neatly - a good indicator.
Shop from trustworthy sellers. Ask friends or family to recommend a reliable supplier, and do not be tempted by sudden discounts. Sapphires are very expensive stones, and you should be sure that you are completely satisfied with the jewelry before you decide to purchase.
On the jewelry market you can easily find synthetic sapphires (the label will indicate “gt” or “s”, i.e. synthetic). The question often arises: what is the difference between synthetic and artificial sapphires and natural ones? How to distinguish a real mineral from an artificially grown one? What are their similarities and differences, how much do the prices for natural and synthetic stones differ?
Reason for creating hydrothermal sapphires
A natural gemstone with a blue color, rare in nature, is quite expensive, and therefore the issue of developing an analogue has been on the agenda for a long time among jewelers. We can say that, along with the price, the reason for the synthesis of such a mineral is its rare color. In order to obtain blue shades, dyeing and heating to very high temperatures are used. As a result, there are currently many synthetic stones on the jewelry market, created to meet the high demand for inexpensive blue mineral analogues.
Similarity to natural sapphires
Hydrothermal sapphires are made from corundum. Another name for this method of growing minerals is nanosapphire. (Often on labels you can find the name of the insert “corundum” and depending on the color it will be synthetic sapphire - blue or ruby - red).
Both natural and hydrothermal minerals have the same chemical formula - aluminum oxide - Al2O3 (corundum).
They have the same hardness on the Mohs scale, 9 out of 10 points.
Identical properties in terms of the fragility of the mineral, which causes difficulties in its jewelry processing.
How to distinguish natural sapphire from artificial?
In the jewelry market, it is not customary to pass off artificial stones as natural ones. Therefore, when choosing jewelry, you need to be careful and know what is inserted into it - a natural gem or an artificially grown mineral?
The most basic difference lies in the origin of the mineral. Natural, as is obvious from the name itself, is found and extracted from nature (it was formed in difficult conditions over many years). Synthetic or hydrothermal is obtained in the laboratory in a short period of time (grown in 2-3 weeks).
To create a hydrothermal mineral, all the same chemical components are used as in natural minerals, and similar conditions are used - high temperature and pressure.
A mineral grown in laboratory conditions is of higher quality, it does not have impurities that are possible in natural conditions, and also, due to constant monitoring of the process, the crystal is cleaner, without cracks and air bubbles.
Synthetic has a more durable color, unlike natural. It is not affected by UV rays, so it can be worn around the clock.
The difference in price is probably the most important thing. With equal characteristics it will be about 10 times. That is, if a natural sapphire costs $400, its hydrothermal “brother” of the same size will cost only $40.
Diffusion and declassed sapphire
Diffusion is a chemical and physical process of penetration of molecules of a substance into the molecules of another substance. Diffusion is used as a method for refining precious stones, including for refining fancy types of sapphire.
Fancy sapphire - any type except blue.
In order to refine star sapphire, diffusion with beryllium salts is used. As a result of heating and creating high pressure, beryllium salts penetrate into it in such a way that they “impregnate” the stone through and through. The effect of asterism is noticeably enhanced.
Methods for diffusion refining of sapphires can be of two main types: “impregnation” of the outer layer of corundum, when the true color becomes invisible underneath it, and “internal” diffusion, when at high temperatures internal inclusions in corundum, such as titanium and chromium, dissolve and coloring occurs mineral.
In any case, the refinement of corundum by diffusion methods is legal, if after this the gem is not presented as natural, but it is honestly indicated that these manipulations were carried out with it. Otherwise, it will be misleading or deceiving the consumer.
Declassed should not be confused with diffusion or synthetic. This gem is natural, but of low quality. So, it is cloudy and/or opaque. Quality characteristics, of course, affect its price, although it may be more expensive than synthetic ones. The label usually says “decl,” which means “declassed.”
Artificial sapphire - what to look for when choosing?
If you decide to purchase jewelry with just such an insert, then all that remains is to decide on the color and cut. The artistic component will play a big role in the price, so the choice should be based primarily on it. The most expensive are the types of cutting of transparent stones, which reveal their beauty and make you admire the play of light created by the faces.
In jewelry stores, it is not customary to pass off any other materials as hydrothermal. In workshops that make expensive jewelry to order - even more so. And of course, you should not buy jewelry second-hand or in dubious places, where instead of synthetic (not to mention natural) minerals they can sell inserts made of glass or a similar material.
Designations on jewelry tags
First of all, we note that the designations on jewelry tags refer to precious stones of natural origin. The first number indicates the number of stones in the product, 1, 2, etc. Then the name of the stone is abbreviated. For example, Sp. means sapphire and that the stone is natural, natural. Sp.ob. – means diffusion or ennobled. Manufacturers also “sin” by indicating Sp. cor. – that is, corundum, which means that the product contains a hydrothermal mineral. Next, the tag indicates the shape of the cut - for example, Gr - pear, Kv - square, Tk - triangle. Then there are the digital characteristics of the gemstone - weight, color, clarity.
Hydrothermal, like all synthetic minerals, do not (and cannot have) the digital characteristics of color and purity on jewelry tags that are inherent in natural ones!
If there is an abbreviation "about." or "cor." – synthetic mineral. How to distinguish a sapphire from a fake - see the answer to this question.
Sapphire is rightfully considered one of the most beautiful precious stones. In ancient times, it was called a frozen drop of the elixir of eternal youth and immortality, accessible only to the gods. In nature, sapphires exist in a wide variety of colors and shades: from colorless, yellow and orange to purple and even black. But still, the most valuable stones are blue and dark blue; it is not without reason that the word “sapphire” itself translated from Greek means “blue”.
The cost of a sapphire, like many other precious stones, is largely determined by its origin. If Burma (Myanmar) is synonymous with quality for another precious corundum - ruby, then Kashmir is traditionally considered the birthplace of the most beautiful sapphires. The deep blue color of a real Kashmir sapphire is magnificent. Its peculiar velvety cornflower blue hue partly hides the transparency of the stone, giving it a mysterious appearance; it seems as if the gem is slightly shrouded in a milky mist. This unusual appearance of Kashmir sapphire is given by the tiny crystals and cavities present in the natural stone, which are difficult to distinguish even under a microscope.
They say that anyone who has seen the color of a natural Kashmir sapphire at least once will never confuse it with any other. The color of these stones is considered standard, and when sapphires mined in other places are assessed by color, they are invariably compared with those from Kashmir. Unlike other sapphires, stones from Kashmir do not change their color under artificial light. They also have the most pronounced zonal color characteristic of sapphires, in which the color in the stone is not distributed evenly, but over parallel layers.
Of course, not all sapphires from Kashmir are so good, so even a certificate confirming the origin is not a guarantee of the high quality of the stone. Although all Kashmir sapphires weighing more than 10 carats are very expensive.
Sapphires from Sri Lanka and Myanmar are also highly prized. Burmese stones have a more saturated ultramarine color, and soft cornflower blue, often with a violet tint, Ceylon gems, although they look paler than Kashmiri ones, are particularly clean and transparent. In both of them, characteristic inclusions of rutile are often found - the so-called “silk”. These needle-shaped fibers, forming an angle of about 60 degrees when crossing, are visible through a magnifying glass.
“Silk” in sapphire (as well as in ruby) indicates the natural origin of the stone, but if such inclusions are visible to the naked eye, this significantly reduces its value. The exception is when rutile fibers in the stone form a star. Such gems are called star-shaped; They are rare in nature and are highly valued. A distinctive feature of sapphires from Sri Lanka are also inclusions of zircon, which is explained by the co-occurrence of minerals on this island. In addition, natural Ceylon sapphires, due to the presence of chromium, acquire a purple hue under the light of an ordinary electric lamp.
Sapphires from Thailand are often called "Siamese". They differ from Kashmiri ones in their darker blue color and lack of velvety shine. Australian sapphires are the darkest and can appear almost black in artificial light. These stones are considered the cheapest natural sapphires. Although Australia accounts for about 80% of the world's production of these gems, their value represents approximately 25% of the total value of mined sapphires.
At the end of the 19th century, sapphire deposits were discovered in the USA (Montana). The color of American gemstones varies from blue to cornflower blue and almost turquoise, but they can be distinguished by their characteristic grayish metallic luster. Despite all the variety of natural sapphires, an experienced jeweler can easily determine the homeland of the gem by the subtle differences in shades and shine.
There are many ways to refine corundum, including sapphires. Using heat treatment, unnecessary shades are eliminated and color intensity is changed. This method is especially widely used for brightening dark-colored Australian sapphires. When calcined under certain conditions, lightly colored and colorless gems acquire a stable blue color. Nowadays, it is even possible to eliminate or create “silk” in natural sapphires. Cracks in cut stones are filled with resins, lead glass or plastic, and oiled with the addition of dye.
Thermal treatment of corundum leaves so-called “fire marks”, distinguishable by microscopic examination. Under the influence of high temperature, liquid and gas inclusions in natural stone disappear, and the zonal color characteristic of sapphires becomes more contrasting. By these and a number of other signs, experts can easily distinguish refined stones. Heat treatment of natural stones is considered quite acceptable, but if it turns out that a large (and therefore very expensive) sapphire has been refined, its price will drop sharply.
Of the natural stones, blue spinel and sapphire are most similar. A refractometer, a device for measuring the refraction of light, will help you distinguish both stones from sapphire. The refractive index of tanzanite is -1.7, spinel - 1.72; and for sapphire this figure is much higher (1.76-1.77). Blue spinel is too dark and can only be confused with low quality sapphires, while tanzanite has a slight reddish tint. , and other blue stones differ even more from sapphire both in color and in basic properties. In addition, we should not forget that sapphire is corundum, which ranks second in hardness (9) after diamond, so it is harder than any natural imitation.
The first experiments on the artificial synthesis of corundum were carried out at the end of the 19th century. In the middle of the last century, the USA mastered the production of synthetic star sapphires and. Currently, artificial jewelry corundum of a wide variety of colors is widely produced throughout the world, including in Russia. One of the varieties of blue synthetic corundum has the romantic name “sapphire of hope”.
Distinguish artificial sapphires from natural possible by the absence of natural inclusions, the presence of impurities and gas bubbles, and curved color lines. Many synthetic sapphires use titanium, so if you expose the stone to ultraviolet light, it will appear greenish. But synthesis methods are constantly being improved and, often, only a specialist can unambiguously determine the artificial origin of a stone.
To imitate sapphires, both rhinestones and composite stones are often used. Distinguish rhinestones from natural sapphires in terms of low strength, gas bubbles present in the glass, single refraction and other indicators, it is not so difficult. Composite stones are jewelry stones that consist of two (doublets) or several parts. At the top of such a product there may be a real sapphire, glued by the master onto a substrate made of cheaper artificial or natural stone, and possibly even ordinary blue glass.
If such a fake is in a closed frame, checking with a refractometer will not yield anything: the device will give the same indicators as for a real solid sapphire. The gluing plane, which coincides with the edge of the stone from above, will be practically invisible during a superficial inspection, but through a magnifying glass the connection line can be easily detected. And if you look at a composite stone in profile, in sufficiently bright lighting it will be noticeable that the top and backing do not match in color.
A high-quality natural sapphire can cost hundreds or even thousands of dollars per carat, while stones of exceptional quality and size sell for millions at auction. Many of us, when traveling to Thailand, Myanmar and other countries rich in precious stones, believe that they sell only natural gems and very inexpensively. But the jewelry market has always been one of the most international, and nowadays it has absolutely no boundaries, so a street vendor somewhere in Bangkok knows how much his goods actually cost, no worse than a seller in a European luxury jewelry store.
Instructions
If you want to know if yours is sapphire, use a device that measures the refraction of light - a refractometer. Sapphire has a refractive index of approximately 1.762-1.778. Don't forget that this is corundum. In terms of hardness, it ranks second after diamond, which is why sapphire is all its imitations. If you have a stone with a hardness of 8.5 on the Moss scale, run it over the corundum. There will not be the slightest trace left on a real sapphire. Aquamarine and tanzanite are most similar to blue corundum, but tanzanite has a reddish tint, and aquamarine has a greenish tint.
Take a close look at your stone if you want to distinguish an artificial sapphire from a natural one. The artificial one does not have any inclusions; gas bubbles are visible in it. To produce synthetic stones, many manufacturers use titanium, so under ultraviolet rays the sapphire will turn greenish. Natural blue corundum has white highlights, which the synthetic mineral lacks.
A distinctive feature of some artificial sapphires is curvilinear zoning, which is not found in natural stones. Also, synthetic minerals may have inclusions of copper. Hydrothermal corundums have an irregular growth microstructure. However, manufacturers are trying to improve the process of growing stones, so only a specialist can confidently distinguish a mineral from a natural one.
Synthetic stones are more than natural ones. The chemical composition of natural and artificial minerals is the same, but grown ones do not have external defects and inclusions, their color is purer and deeper. Real stones have a certificate - another sign that distinguishes them from fakes. Consider the price of your sapphire; real blue corundum costs anywhere from several hundred to several thousand dollars.
Video on the topic
Sources:
- Synthetic, artificial stones, fakes, their difference from natural ones visually without examination, ennoblement of natural material
- how to distinguish natural stones from non-natural ones
- How to determine whether a sapphire has a natural or diffuse star
Tip 2: How to distinguish natural from artificial sapphire
It has a heterogeneous structure with noticeable inclusions. It has no gas bubbles and its hardness is similar to that of diamond. High-quality natural stone costs from several hundred to several thousand dollars per carat.
Instructions
It can be difficult for someone uninitiated in all the intricacies of mining and finishing to distinguish natural sapphire from artificial sapphire. However, there are certain signs characteristic of natural stones that even an inexperienced buyer can identify. But if you are planning to purchase expensive jewelry, then it is better to show the product to a specialist before purchasing.
Sapphire is a gemstone whose color varies from colorless to violet, and only a rare natural stone does not change its color under artificial light. Therefore, you need to look at the stone first in daylight, and then in the light of an ordinary electric lamp. Unnatural stone will change its color. A real Kashmir sapphire has a peculiar velvety cornflower blue hue. Burmese stones and Ceylon gems are distinguished by their so-called “silk”. We are talking about needle-shaped fibers, which, intersecting, form an angle of 60°. And this can be seen if you arm yourself with a magnifying glass.
Now carefully examine the stone for inclusions and gas bubbles. Artificial stone, as a rule, is more beautiful; it has a uniform structure with an admixture of gas bubbles. Natural sapphire is less susceptible to defects, but at the same time noticeable inclusions are found in it.
Jewelry with natural precious stones usually costs a lot of money. A large natural sapphire of high purity without many inclusions is not so common in nature, and the cost of each such stone is very high. Jewelers set the task of learning how to grow artificial stones in their workshops, and they succeeded very well. Today you can find jewelry with artificial rubies, emeralds or sapphires on sale at low prices. Let's figure out together how such stones are produced and how to distinguish natural sapphire from synthetic one.
Synthetic sapphire - grown sapphire
Artificial sapphires are not actually grown, but boiled. The basis is aluminum oxide, a white powder, to which impurities are added. In general, aluminum oxide is the raw material for making aluminum, but this unremarkable white powder also has another amazing quality - if it is heated to the right temperature, it will turn into sapphire. The temperature for producing synthetic sapphires is 2200 degrees Celsius. It is worth noting that this is not the only way to obtain sapphires, but only one of them.
Natural sapphires were formed millions of years ago. Small inclusions of aluminum oxide turned into sapphires under the influence of high temperatures. So when you buy jewelry with a real sapphire, you are purchasing a stone with an incredibly long and interesting history.
As for artificial sapphires, the growing time depends on their size. In general, artificial sapphire is grown in a couple of weeks. Crystallization occurs at a rate of 4 mm per hour. The larger the sapphire, the longer it will take to grow it. After growing a large crystal, it is cut into pieces using special equipment and processed.
How to distinguish natural sapphire from artificial
There is nothing wrong with artificial sapphires if the jewelry manufacturer does not hide the fact of using artificial sapphires from buyers. Artificial sapphires have properties identical to natural stones. The physical, chemical and optical properties of such synthetic stones are almost identical to natural ones. Synthetic sapphire is not some kind of blue-colored glass, but a real sapphire, simply obtained artificially.
That is why, in some cases, only an experienced jeweler can distinguish a synthetic stone from a natural one, and then only with the use of special equipment, because these stones are no different in their characteristics from natural ones.
To determine the authenticity of a stone, a specialist can examine it using a magnifying glass. The sapphire is immersed in a transparent container with a solution (monobromonaphthalene), which, in turn, is placed on a white sheet. Man-made sapphires will have curved inclusions, while natural sapphires will have straight stripes. Thus, the first sign of a synthetic stone is the presence of curved inclusions.
Natural sapphires also have whitish reflections. Artificial stones lack these properties and have a greenish tint in ultraviolet light.
By the way, very often completely different stones are passed off as synthetic sapphires. This is where a refractometer comes to the aid of sapphire lovers. The value of the refractive index of light for both natural and synthetic sapphire will be from 1.762 to 1.778.
And lastly, if you are offered a piece of sapphire jewelry that is significantly lower than the market value, this is a reason to think about the authenticity of the crystals in it.
