Gemstones

Jai Ganesh · Yesterday 18:32:48

Gemstones

Gist

The 12 gemstones, known as birthstones, correspond to each month of the year, with modern lists often including alternatives for some months, featuring Garnet (Jan), Amethyst (Feb), Aquamarine (Mar), Diamond (Apr), Emerald (May), Pearl/Alexandrite (Jun), Ruby (Jul), Peridot (Aug), Sapphire (Sep), Opal/Tourmaline (Oct), Topaz/Citrine (Nov), and Tanzanite/Zircon/Turquoise (Dec), representing different virtues and qualities.

While diamonds are known as the "king of all gems" for their hardness and brilliance, the Ruby is most often called the "King of Gemstones" (or Ratnaraj in Sanskrit) due to its deep red color, rarity, association with royalty, power, and vitality, and highest per-carat price among colored stones. Both hold prestigious titles, but the ruby's fiery red hue and historical significance often earn it the "king" crown.

Goshenite is a colorless gem variety of beryl. It is sometimes called the “mother of all gemstones”because it can be transformed into other gems, such as emerald, morganite, or bixbite. Goshenite is also referred to as the purest form of beryl since there are generally no other elements present in the stone.

Summary

A gemstone is any of various minerals highly prized for beauty, durability, and rarity. A few noncrystalline materials of organic origin (e.g., pearl, red coral, and amber) also are classified as gemstones.

Gemstones have attracted humankind since ancient times, and have long been used for jewelry. The prime requisite for a gem is that it must be beautiful. The beauty may lie in colour or lack of colour; in the latter case, extreme limpidity and “fire” may provide the attraction. Iridescence, opalescence, asterism (the exhibition of a star-shaped figure in reflected light), chatoyance (the exhibition of a changeable lustre and a narrow, undulating band of white light), pattern, and lustre are other features that may make a gemstone beautiful. A gem must also be durable, if the stone is to retain the polish applied to it and withstand the wear and tear of constant handling.

In addition to their use as jewelry, gems were regarded by many civilizations as miraculous and endowed with mysterious powers. Different stones were endowed with different and sometimes overlapping attributes; the diamond, for instance, was thought to give its wearer strength in battle and to protect him against ghosts and magic. Vestiges of such beliefs persist in the modern practice of wearing a birthstone.

Of the more than 2,000 identified natural minerals, fewer than 100 are used as gemstones and only 16 have achieved importance. These are beryl, chrysoberyl, corundum, diamond, feldspar, garnet, jade, lazurite, olivine, opal, quartz, spinel, topaz, tourmaline, turquoise, and zircon. Some of these minerals provide more than one type of gem; beryl, for example, provides emeralds and aquamarines, while corundum provides rubies and sapphires. In virtually all cases, the minerals have to be cut and polished for use in jewelry.

Except for diamond, which presents special problems because of its very great hardness (see diamond cutting), gemstones are cut and polished in any of three ways. Agate, opal, jasper, onyx, chalcedony (all with a Mohs hardness of 7 or less) may be tumbled; that is, they may be placed in a cylinder with abrasive grit and water and the cylinder rotated about its long axis. The stones become polished but are irregular in shape. Second, the same kinds of gemstones may instead be cut en cabochon (i.e., with a rounded upper surface and a flat underside) and polished on water- or motor-driven sandstone wheels. Third, gemstones with Mohs hardness of more than 7 may be cut with a carborundum saw and then mounted in a holder (dop) and pressed against a lathe that can be made to revolve with extreme rapidity. The lathe carries a point or small disk of soft iron, which can vary in diameter from that of a pinhead to a quarter of an inch. The face of the disk is charged with carborundum grit, diamond dust, or other abrasives, along with oil. Another tool used to grind facets is the dental engine, which has greater flexibility and sensitiveness than the lathe. The facets are ground onto the stone using these tools and then are polished as described above.

Of decisive significance for the modern treatment of gemstones was the kind of cutting known as faceting, which produces brilliance by the refraction and reflection of light. Until the late Middle Ages, gems of all kinds were simply cut either en cabochon or, especially for purposes of incrustation, into flat platelets.

The first attempts at cutting and faceting were aimed at improving the appearance of stones by covering natural flaws. Proper cutting depends on a detailed knowledge of the crystal structure of a stone, however. Moreover, it was only in the 15th century that the abrasive property of diamond was discovered and used (nothing else will cut diamond). After this discovery, the art of cutting and polishing diamonds and other gems was developed, probably in France and the Netherlands first. The rose cut was developed in the 17th century, and the brilliant cut, now the general favourite for diamonds, is said to have been used for the first time about 1700.

In modern gem cutting, the cabochon method continues to be used for opaque, translucent, and some transparent stones, such as opal, carbuncle, and so on; but for most transparent gems (especially diamonds, sapphires, rubies, and emeralds), faceted cutting is almost always employed. In this method, numerous facets, geometrically disposed to bring out the beauty of light and colour to the best advantage, are cut. This is done at the sacrifice of material, often to the extent of half the stone or more, but the value of the gem is greatly increased. The four most common faceted forms are the brilliant cut, the step cut, the drop cut, and the rose cut.

In addition to unfaceted stones being cabochon cut, some are engraved. High-speed, diamond-tipped cutting tools are used. The stone is hand-held against the tool, with the shape, symmetry, size, and depth of cut being determined by eye. Gemstones can also be made by cementing several smaller stones together to create one large jewel.

In some cases, the colour of gemstones is also enhanced. This is accomplished by any of three methods: heating under controlled conditions, exposure to X rays or radium, or the application of pigment or coloured foil to the pavilion (base) facets.

In recent times various kinds of synthetic gems, including rubies, sapphires, and emeralds, have been produced. Two methods of fabrication are currently employed, one involving crystal growth from solution and the other crystal growth from melts.

Details

A gemstone (also called a fine gem, jewel, precious stone, semiprecious stone, or simply gem) is a piece of mineral crystal which, when cut or polished, is used to make jewelry or other adornments. Certain rocks (such as lapis lazuli, opal, and obsidian) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) may also be used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some softer minerals such as brazilianite may be used in jewelry because of their color or luster or other physical properties that have aesthetic value. However, generally speaking, soft minerals are not typically used as gemstones by virtue of their brittleness and lack of durability.

Found all over the world, the industry of coloured gemstones (i.e. anything other than diamonds) is currently estimated at US$1.55 billion as of 2023 and is projected to steadily increase to a value of $4.46 billion by 2033.

A gem expert is a gemologist, a gem maker is called a lapidarist or gemcutter; a diamond cutter is called a diamantaire.

Characteristics and classification

A collection of gemstone pebbles made by tumbling the rough stones, except the ruby and tourmaline, with abrasive grit inside a rotating barrel. The largest pebble here is 40 mm (1.6 in) long.
The traditional classification in the West, which goes back to the ancient Greeks, begins with a distinction between precious and semi-precious; similar distinctions are made in other cultures. In modern use, the precious stones are emerald, ruby, sapphire and diamond, with all other gemstones being semi-precious. This distinction reflects the rarity of the respective stones in ancient times, as well as their quality: all are translucent, with fine color in their purest forms (except for the colorless diamond), and very hard with a hardness score of 8 to 10 on the Mohs scale. Other stones are classified by their color, translucency, and hardness. The traditional distinction does not necessarily reflect modern values; for example, while most garnets are relatively inexpensive, a green garnet called tsavorite can be far more valuable than a mid-quality emerald. Another traditional term for semi-precious gemstones used in art history and archaeology is hardstone. The use of the terms "precious" and "semi-precious" in a commercial context is arguably misleading, as it suggests that certain stones are more valuable than others, which is not always reflected in their actual market value—although the terms may generally be accurate when referring to desirability.

In modern times gemstones are identified by gemologists, who describe gems and their characteristics using technical terminology specific to the field of gemology. The first characteristic a gemologist uses to identify a gemstone is its chemical composition. For example, diamonds are made of carbon (C), while sapphires and rubies are made of aluminium oxide (Al2O3). Many gems are crystals which are classified by their crystal system such as cubic or trigonal or monoclinic. Another term used is habit, the form the gem is usually found in. For example, diamonds, which have a cubic crystal system, are often found as octahedrons.

Gemstones are classified into different groups, species, and varieties. For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples of beryl varieties include emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow), and morganite (pink).

Gems are characterized in terms of their color (hue, tone and saturation), optical phenomena, luster, refractive index, birefringence, dispersion, specific gravity, hardness, cleavage, and fracture. They may exhibit pleochroism or double refraction. They may have luminescence and a distinctive absorption spectrum. Gemstones may also be classified in terms of their "water". This is a recognized grading of the gem's luster, transparency, or "brilliance". Very transparent gems are considered "first water", while "second" or "third water" gems are those of a lesser transparency. Additionally, material or flaws within a stone may be present as inclusions.

Value

Gemstones have no universally accepted grading system. Diamonds are graded using a system developed by the Gemological Institute of America (GIA) in the early 1950s. Historically, all gemstones were graded using the naked eye. The GIA system included a major innovation: the introduction of 10x magnification as the standard for grading clarity. Other gemstones are still graded using the naked eye (assuming 20/20 vision).

A mnemonic device, the "four Cs" (color, cut, clarity, and carats), has been introduced to help describe the factors used to grade a diamond. With modification, these categories can be useful in understanding the grading of all gemstones. The four criteria carry different weights depending upon whether they are applied to colored gemstones or to colorless diamonds. In diamonds, the cut is the primary determinant of value, followed by clarity and color. An ideally cut diamond will sparkle, to break down light into its constituent rainbow colors (dispersion), chop it up into bright little pieces (scintillation), and deliver it to the eye (brilliance). In its rough crystalline form, a diamond will do none of these things; it requires proper fashioning and this is called "cut". In gemstones that have color, including colored diamonds, the purity, and beauty of that color is the primary determinant of quality.

Physical characteristics that make a colored stone valuable are color, clarity to a lesser extent (emeralds will always have a number of inclusions), cut, unusual optical phenomena within the stone such as color zoning (the uneven distribution of coloring within a gem) and asteria (star effects).

Apart from the more generic and commonly used gemstones such as from diamonds, rubies, sapphires, and emeralds, pearls and opal have also been defined as precious in the jewellery trade. Up to the discoveries of bulk amethyst in Brazil in the 19th century, amethyst was considered a "precious stone" as well, going back to ancient Greece. Even in the last century certain stones such as aquamarine, peridot and cat's eye (cymophane) have been popular and hence been regarded as precious, thus reinforcing the notion that a mineral's rarity may have been implicated in its classification as a precious stone and thus contribute to its value.

Today the gemstone trade no longer makes such a distinction. Many gemstones are used in even the most expensive jewelry, depending on the brand-name of the designer, fashion trends, market supply, treatments, etc. Nevertheless, diamonds, rubies, sapphires, and emeralds still have a reputation that exceeds those of other gemstones.

Rare or unusual gemstones, generally understood to include those gemstones which occur so infrequently in gem quality that they are scarcely known except to connoisseurs, include andalusite, axinite, cassiterite, clinohumite, painite and red beryl.

Gemstone pricing and value are governed by factors and characteristics in the quality of the stone. These characteristics include clarity, rarity, freedom from defects, the beauty of the stone, as well as the demand for such stones. There are different pricing influencers for both colored gemstones, and for diamonds. The pricing on colored stones is determined by market supply-and-demand, but diamonds are more intricate.

In the addition to the aesthetic and adorning/ornamental purpose of gemstones, there are proponents of energy medicine who also value gemstones on the basis of their alleged healing powers.

Additional Information

Gemstone symbolism refers to the cultural, historical, and spiritual associations between specific gemstones and concepts like healing, protection, love, and strength. This tradition dates back to ancient civilizations, where gemstones were prized not only for their beauty but for their perceived metaphysical properties. These beliefs influenced how gemstones were used — from royal jewelry and religious artifacts to personal talismans and medicinal treatments.

Today, many people choose gemstones based on these symbolic meanings to guide their purchases or for personal reasons, whether for birthstone jewelry or engagement rings.

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Gemstones

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