Stones by zodiac signs

How to distinguish real stone from glass?

Precious stones have always served as a reliable and very compact investment of capital. It is not surprising that they were often tried to forge – sometimes successfully, sometimes not so much. Counterfeits can sparkle and sparkle just as well as diamonds. How do you distinguish real stones from fake ones? Dmitry Mamontov
Getty Images The development of methods by which one can distinguish real stones from fake ones is the science of gems, precious and ornamental stones – gemology. In fact, the term “counterfeits” when applied to precious stones is not entirely correct – these can be either imitations that only at first glance resemble the original, or very similar synthetic stones in all properties, which can only be distinguished from the original with the help of a complex modern laboratory equipment. The chief expert of the Gemological Center of Moscow State University, Alexander Stolyarevich, told TechInsider about some of the secrets of gemology. ADVERTISEMENT – PRODOLJENIE NIJE

Simulations

This is the simplest version of fakes. They only resemble real precious stones in appearance. For example, the simplest imitation of diamonds is optical glass rhinestones, another well-known option is cubic zirconia (cubic zirconium oxide). But in their physical and chemical properties, imitations differ from the original. “Recently, they brought us a pink stone for examination, supposedly a “unique diamond weighing about 90 carats,” says Alexander. “However, almost immediately it became clear that it was not a diamond, but cubic zirconia. But still, the entire examination had to be carried out in front of the owner, with detailed explanations. Fortunately, it’s quite easy to distinguish them, even by density: cubic zirconia is much heavier.” ADVERTISEMENT – PRODOLJENIE NIJE
Optical properties of gems
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Composite stones

These are also imitations, but of a slightly different kind. They are glued together from several parts, each of which can be made of glass, natural or synthetic stone. Here we are talking not only about appearance, but also about hardness, refractive index and other characteristics. This method produces stones of bright, intense colors by gluing the top layer of natural pink corundum and the bottom layer of bright red synthetic corundum; Combinations of garnet with colored glass, and lightly colored beryl with synthetic emerald are common. This two-piece design is called a doublet. You can distinguish a doublet from a natural stone by the glue “seam” on the girdle (the belt of a faceted stone) under a magnifying glass or microscope. Sometimes a stone is glued together from three parts – this is a triplet. Often this design is used quite “officially” – to protect the stone from unfavorable external factors. For example, a thin plate of fragile and moisture-sensitive noble opal is glued onto a durable base, and covered on top with a “lid” of glass or quartz. But, of course, in such cases it is always stipulated that this is an opal triplet, and not just opal. ADVERTISEMENT – PRODOLJENIE NIJE

Ennobled stones

But why glue if there are plenty of natural stones? True, the appearance of most of them is “not very good”, but this can be corrected – through the process of refining, that is, improving the consumer properties of the stone (appearance, durability), in addition to the actual cutting and polishing. These include dyeing, bleaching, coating, impregnation, heat treatment, pressure treatment, diffusion treatment, irradiation (gamma, beta or neutron) and other processes. For some stones, such processing has been used since ancient times (for example, impregnating emeralds with oil or heat treating aquamarines to obtain a pure blue hue) and is officially legalized by the rules of various gemological associations. But still, such stones must be marked accordingly. For example, according to the rules of the International Colored Gemstone Association (ICA, International Colored Gemstone Association), natural stones are designated by the letter N (Natural), refined using traditional, historically established methods, a list of which is in the relevant reference books, by the letter E (Enhanced), and the rest are called processed and are designated by the letter T (Treated) with a decoding of all processes used. Gemologist’s Arsenal One of the main tools of a gemologist is a magnifying glass and a microscope. They allow you to see the characteristics of crystal growth, various inclusions and defects. Often this is enough to identify the stone with high reliability. For example, a demantoid (green garnet) is almost uniquely determined by inclusions of bissolite of the “horsetail” type.
The refractive index is determined using a refractometer by measuring the angle of total internal reflection of light from one of the faces of the stone. But dispersion (the ability to decompose white light into components, it is called the “game” of a stone) is assessed mainly by eye. A spectroscope allows you to determine the basic chemical composition of a stone using absorption lines.
An important indicator is density, which is measured by hydrostatic weighing (Archimedes’ method) – that is, weighing in air and water. You can also calculate the density using the geometric method: to do this, you need to weigh, then measure the cut stone with a caliper and calculate its volume using special formulas in accordance with the shape of the cut. Sometimes a set of heavy liquids with known densities is used: if the stone does not sink, then it is less dense; if it sinks, then it is more dense.
Pleochroism (that is, the different colors of anisotropic crystals when viewed along different directions) is determined using a dichroscope – a device that transmits two perpendicularly polarized beams. Another instrument for studying optical anisotropy is a polariscope, in which a sample is placed between crossed polarizers. Based on the picture visible through the polariscope, we can conclude that the structure of the crystal lattice of the anisotropic stone is symmetrical.
An important tool is a UV lamp. By fluorescence in UV rays one can judge the chemical composition. Let’s say a blue synthetic spinel glows red when exposed to UV light. But natural blue spinel contains iron impurities, which “quench” the glow.
But hardness, one of the main characteristics of a stone, is measured using a set of hardness pencils only in the most extreme cases (we are talking about faceted stones). True, it can be indirectly assessed by the “sharpness” of the edges of the facets – for example, imitation diamonds have more rounded edges compared to real ones. Many stones use heat treatment (called “heated” stones by jewelers) and irradiation, or a combination of both, to change the color or clarity of many stones. Quite often, diffusion staining is used to “improve” weakly colored sapphires in solutions of cobalt salts. In this case, only a thin layer is painted, so if you put the stone on a white sheet of paper, a bright “skeleton” on the edges of the faces becomes visible. Recently, processes of diffusion coloring to great depths using beryllium compounds have appeared. This is how expensive varieties of sapphires are obtained – bright pink-orange (“Padparadscha”). It is possible to distinguish such a stone from a natural one only with the help of special laboratory equipment that allows you to detect traces of beryllium. To do this, a microscopic amount of material is evaporated from the surface of the stone using a laser (ablation), and the resulting “vapor” is studied using spectrophotometry or mass spectrometry. 25 January 2020 Natural stones are marvelous, beautiful and unique created by nature. Natural stones, which come in a variety of colors, shades and shapes, melt with their own inexhaustible natural forces. Every time sanding and polishing, the roughness and invisible surface of the stones are transformed into smooth and shiny, revealing the true beauty and charm, attracting the hearts of people. As much as there is light, there are also carved imitations and parts of natural stones – expensive and artificial ones. “There is no more employment than profit, less precious stones” – if you say Pliny the Elder. At this time, the most widespread operation is the replacement of natural stones with synthetic ones, which are produced on an industrial scale. Synthetic stones almost completely replicate the physical characteristics and appearance of natural stones, and are much cheaper to construct. Today, synthetic emeralds, rubies, sapphires, oleksandrites, as well as synthetic diamonds are actively growing. Synthetic stones with a good reputation can, just as they are expensive, increase in price and become costly, and rare specimens can become collector’s items. Natural stones – how to cut them into granules? Let’s look at a number of simple ways: In order to independently determine what is in front of you: natural stone, synthetic, plastic or hard, you will need: a bright lamp, a 10-fold magnifying glass, cork, water, vags, a magnet and sirniki. Well, you added a natural stone (check, first of all, in a jewelry store or gem shop, you are unlikely to give it to someone who has already bought it, but was in doubt, then we check the booth):

  1. Take the stone in your hands, you can touch it with mine. Natural stones are cooler than artificial ones and heat up longer. In this way you can cut, for example, quartz, Georgian crystal, amethyst and aquamarine.
  2. Look at the stone under a 10x magnifying glass. What can you do? For example, let’s take emerald, as you see spiral patterns and tubular parts of the baby, which means that this is a synthetic particle. Natural rubies have zigzag-like cracks, while stones have straight, even cracks. The monthly stone (adularia) has a spherical structure. Aquamarine has presence of inclusions, its appearance suggests a white chrysanthemum. Natural amethyst is characterized by natural inclusions and defects. Yes, yes, defects! In general, if in front of you is a stone, for example, not expensive, for example, the same amethyst or jasper, or jade, or agate, and you see that it has roughness, internal cracks, dimples, holes with a kind of snow coating, then this speaks of the authenticity and natural origin of the stone. If you have an expensive specimen in front of you, without the defects listed above, then in this case only an expert gemologist can give an accurate conclusion about the origin.
  3. The color of the stone is of great importance. If you look closely at a ruby, it will appear paler from one angle than from the other. Look at aquamarine from different angles; real aquamarine changes its color slightly. You can also check citrine. But peridot has a uniform color. Lapis lazuli has a smooth blue color. You can check natural turquoise by rubbing it with a cloth soaked in hot water; if the fabric is stained, then this is a cheap fake (read more about turquoise in the article “About Turquoise”).
  4. We check the diamond with a bright lamp, directing the light perpendicularly – the edges of the cut from behind will glow. In ruby, zigzag-shaped cracks do not glow when brightly illuminated. The monthly stone shimmers with lightless flowers, and a “sweet spot” appears in the middle of the stone. A similar effect occurs in labradorite (labradorite).
  5. You can check the mineral by hardness. The right diamond resists the “pressure” of the emery paper. You can’t lose the hairiness of diamonds. If you hold a diamond over an emerald, a sapphire or a glass, they will become stained. Heliodor can remove the trace from the slide.
  6. Let us verify the physical power of stones, for example, electrification. Take a cotton wool and rub it with natural burshtin or topaz. The same stones then begin to attract fragments and fibers. Garnet is filled with magnetic powers. Place the stopper on the valve, put the mineral on it, and then bring the magnet in, the arrow on the valve will begin to wobble.
  7. Let’s check the burshtin – let’s bring the cheesecake to a new flame, the natural smell will not be resinous, the unripe burshtin will become spitting, and when pressed it will become sticky. The little one doesn’t smell like plastic.

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