Myths and legends

How to distinguish natural amethyst from glass?

The work gives characteristics of the amethyst jewelry and ornamental stone. And the main ways to determine the authenticity of an amethyst are discussed both at home and in the laboratory using modern equipment. Amethyst is a crystalline mineral containing silicon dioxide with iron impurities (SiO2). The characteristic properties of the stone are a hardness of 7 on the Mohs scale, a violet tint in color, transparency with a glassy or pearlescent luster, a white streak and a conchoidal fracture. Amethyst often contains inclusions: liquid, gas-liquid and mineral. The shade range of natural amethysts has a wide range – from light pink to dark purple. The color distribution is usually uneven and is characterized by zoning. The color is usually concentrated at the very tip of the head and is more intense due to the presence of iron impurities. Amethyst is a type of quartz, but unlike ordinary quartz, the prismatic facets on amethyst crystals are usually weakly manifested; the facets of rhombohedrons dominate in the cutting of its crystals. Most often, amethysts are shaped like hexagonal crystals or rhombohedrons, similar to rock crystal. Sometimes in nature you can find long prismatic crystals, less often scepter-shaped (of all quartz, this shape is typical for amethyst), reaching a length of up to 35 cm. Most often, minerals are found in geodes of basalt rocks, where amethyst crystals form on the inner walls. The color of natural amethyst is uneven in the form of zones and spots, sometimes yellowish inclusions can be seen. The gem is capable of changing color depending on the lighting angle and temperature. When calcined to 400-500°C, the crystals become yellow or green or colorless with longer exposure. Since this stone is popular nowadays, the question of its falsification arises. How to distinguish a natural amethyst from a fake? Amethyst is a common breed, but its expensive original examples are often counterfeited. A fake gem can be made of plastic or glass. Plastic imitation Plastic can be passed off as amethyst, then the fake can be easily detected. It’s lightweight, warm to the touch, scratch resistant, and inexpensive. Even a non-specialist can distinguish a plastic imitation from a natural amethyst. Amethyst glass Transparent amethysts are replaced with painted crystal glass. By what signs can you distinguish imitation? The glass is easily scratched with a knife and does not damage porcelain and other glass; the rock is evenly colored: natural stone always has zoning, since it grows unevenly, so the pigment and crystals are arranged differently; If you put an amethyst in water, it will acquire a thicker color and turn pale at the edges. The glass will remain unchanged; Natural amethyst heats up slowly when squeezed in your hand. The imitation heats up to human body temperature faster; a glass fake of a mineral changes color in the light and under the rays of the sun; amethyst retains color; air bubbles and microcracks are present inside the original gem; It is impossible to fake them in glass, as well as in synthetic stones. You can examine these signs in more detail using a magnifying glass or under a microscope. Synthetic amethyst Amethyst can be grown artificially. Synthetic amethyst is based on the same silica, the color is identical. Examining such a stone under magnification, we will not find cracks or gas inclusions, but the arrangement of the crystals has a certain character. Experts know about these features. You can distinguish an artificial stone by price and appearance (natural amethyst is not inserted into cheap jewelry). But in general, only special examination will help to distinguish artificial amethyst crystals from natural ones. Purpose of scientific work: conduct an examination of 5-6 samples of real amethyst and its analogues and determine authenticity. Equipment used: optical metallographic microscope with a large depth of focus (MBS-10) (Fig. 1); Mohs scale (Fig. 2); magnifying glass Rice. 1. Optical metallographic microscope Rice. 2. Reference samples of the Mohs scale

  • Sample 1 – stone druses (Fig. 3),
  • Sample 2 – polished amethysts (Fig. 4),
  • Sample 3 – amethyst in a tree-shaped product (Fig. 5),
  • Sample 4 – amethyst ring (Fig. 6).

Rice. 3. Amethyst druzy

Rice. 4. Polished amethyst samples

Rice. 5. Souvenir in the form of an amethyst tree

Rice. 6. Amethyst ring

Checking the authenticity of amethyst at home and in the laboratory. Conducting an experiment.

There are several ways to determine the authenticity of an amethyst at home. It is necessary to take into account the properties of the stone, from which one can draw conclusions about its naturalness. First of all, you should pay attention to visual signs. The appearance of natural stone is characterized by:

The presence of a “natural”, not too bright, uneven purple color. The color of natural stone should not change depending on the lighting; it should retain its shade in both daylight and artificial light. All analyzed samples meet this requirement

Presence of inclusions. Inclusions are clearly visible on druses, and growth crystals are visible on polished amethysts (Fig. 7), therefore they are natural. At magnification (x 32) of a microscope, the ring looks like a homogeneous mass, therefore, based on this, we determine that the amethyst in the ring is not natural.

Rice. 7. Crystal growth on polished amethyst samples

Thermal conductivity

Natural amethyst has low thermal conductivity, so heating occurs slowly. Natural stone, unlike fake stone, will remain cool in your hands for a long time. You can clearly see the difference if you hold a real and fake amethyst in your hands at the same time: the fake stone will become warm very quickly. Sample No. 4 did not pass the authenticity test.

Hardness of natural amethyst on the Mohs scale equal to 7 – this means that this mineral is harder in its properties than many types of steel. Amethyst will retain its texture, uniformity and integrity for many years, because it will not be scratched by everyday dust or sand.

The scratching hardness of amethyst druses according to standard minerals on the Mohs scale (Fig. 8) is 7, so this gem is natural.

The hardness of polished amethysts during the experiment was 7 on the Mohs scale – these samples are genuine.

Rice. 8. Determination of the hardness of amethyst druse on the Mohs scale

The hardness of the wood product is 7, which means these samples are also natural.

The hardness of the ring when scratched (Fig. 9) turned out to be equal to 4, which indicates that the amethyst is fake (this hardness corresponds to fluorite).

Thus, during the examination, the naturalness of amethyst was confirmed by the natural color of the mineral, impurities, thermal conductivity, growth crystals, and hardness. Based on the stated parameters, the authenticity of natural stones was determined and a synthetic analogue was identified.

  • Amethyst is one of the most popular minerals in jewelry. A beautiful violet, lilac, pinkish-violet variety of quartz. Transparent samples are classified as semi-precious, opaque – as ornamental stones. Rare specimens are valued as collectible minerals. Despite its availability, this type of quartz is often counterfeited.

    Imitations and artificial minerals

    Amethyst is not a rare and expensive stone, since there are many rich deposits in the world. Thus, many active fields are located in Germany and Austria, and the gems mined there are beautiful and affordable. Jewelry quality samples are mined in Russia (in the Urals), in Sri Lanka and in Brazil. Brazilian gems are counterfeited more often than others because beautiful gems with high transparency are found there.

    Under the guise of amethyst, they can offer fakes, artificial stones, as well as cheaper minerals, such as fluorite. The grossest fakes – violet glass products. This glass has a bright, even color and an unnatural shine, which immediately reveals it to be a fake. And here there is nothing wrong with synthetic analogues This is a common practice in jewelry making. Usually artificial amethysts are grown on the basis of the same quartz. The grown nugget has the same physical properties and the same chemical composition as its natural counterparts.

    Synthetic gems are good because they allow you to obtain complete analogues of rare amethysts of unusual color and with good transparency

    While these samples can cost as much as diamonds, synthetic gems are much more affordable. However, the buyer must be made aware of the origin of the stone.

    Visual assessment

    To distinguish a fake, the stone needs to be examined carefully. Even a layman can identify an imitation based on a number of signs. First of all, pay attention to the color. The natural mineral has violet, bluish-pinkish, pale reddish-violet color.

    The color can be pale or dark, but it is not overly bright and saturated, unless we are talking about some rare and expensive samples.

    A characteristic feature of imitations is ideality. Perfectly even color, perfect cleanliness without inclusions, shine. All this together gives a feeling of unnaturalness. Natural minerals grown in nature always have some imperfections. These may be opaque areas, microcracks, air inclusions, uneven color.

    When visually examining, remember that the more perfect the stone, the more it looks like painted glass, the more likely it is that it is glass or an artificial imitation

    Authentication

    There are different ways to check the origin of a gem. So, The color of natural amethyst should not change depending on the lighting. Test your stone in daylight and artificial light. If the color changes, then you have an imitation. But under the influence of ultraviolet rays, on the contrary, natural nugget changes color and becomes discolored.

    Check thermal conductivity. For natural mineral is characterized by low thermal conductivity, so it stays cool in your hands for a long time. If the jewelry quickly heats up from the heat of your palms, then this should alert you.

    Its strength can tell a lot about the origin of a stone. So, amethyst has a hardness equal to 7 units on the Mohs scale. This means that even a sharp object will not leave scratches on it. If the scratch remains, then you have ordinary glass in front of you.

    Finally, if you are purchasing expensive jewelry, it is better to check the authenticity in a laboratory. For these purposes, specialists use X-rays and the method of spectral analysis.

    Amethyst is not considered a rare stone, but it is often counterfeited, passing off as glass or cheap varieties of quartz. Try to buy jewelry only from trusted jewelry brands – this is a guarantee that you will not be sold a cheap imitation under the guise of a natural stone.

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