A gemstone or gem (also called a precious or semi-precious stone, or jewel) is a piece of attractive mineral A mineral is a naturally occurring solid chemical substance that is formed through geological processes and that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not have a specific chemical composition, which—when cut and polished—is used to make jewelry Jewellery or jewelry (see American and British English spelling differences) is a form of personal adornment, manifesting itself as necklaces, rings, brooches, earrings and bracelets. Jewellery may be made from any material, usually gemstones, precious metals or shells. Factors affecting the choice of materials include cultural differences and the or other adornments.^[1] However certain rocks In geology, rock is a naturally occurring solid aggregate of minerals and/or mineraloids, (such as lapis lazuli Lapis lazuli (sometimes abbreviated to lapis) is a relatively rare, semi-precious stone that has been prized since antiquity for its intense blue color) and organic Organic chemistry is a discipline within chemistry that involves the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives. These compounds may contain any number of other elements, including hydrogen, nitrogen, oxygen, the halogens as well as materials (such as amber Amber is fossilized tree resin (not sap), which has been appreciated for its color and natural beauty since Neolithic times[citation needed]. Good quality amber is used for the manufacture of ornamental objects and jewelry. There are five classes of amber, defined on the basis of their chemical constituents or jet Jet is a geological material and is considered to be a minor gemstone. Jet is not considered a true mineral, but rather a mineraloid as it has an organic origin, being derived from decaying wood under extreme pressure) are not minerals, but are still used for jewelry, and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their lustre Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. For example, a diamond is said to have an adamantine lustre and pyrite is said to have a metallic lustre. The term is also used to describe other items with a particular sheen (for example, fabric, especially silk and satin, or metals) or other physical properties that have aesthetic value. Rarity is another characteristic that lends value to a gemstone. Apart from jewelry, from earliest antiquity until the 19th century engraved gems An engraved gem is a small gemstone, usually semi-precious, that has been carved, in the Western tradition normally with images or inscriptions only on one face. The engraving of gemstones was a major luxury art form in the ancient world, and an important one in some later periods. Strictly speaking, engraving means carving in intaglio, with the and hardstone carvings Hardstone carving is a general term in art history and archaeology for the carving for artistic purposes of semi-precious stones, also known as gemstones, such as jade, rock crystal , agate, onyx, jasper, serpentine or carnelian, and for an object made in this way. Normally the objects are small, and the category overlaps with both jewellery and such as cups were major luxury art forms; the carvings of Carl Fabergé Peter Carl Fabergé also known as Carl Gustavovich Fabergé in Russia was a Russian jeweller of French origin, best known for the famous Fabergé eggs, made in the style of genuine Easter eggs, but using precious metals and gemstones rather than more mundane materials were the last significant works in this tradition.

Characteristics and classification

The traditional classification in the West, which goes back to the Ancient Greeks Ancient Greek is the historical stage in the development of the Greek language spanning the Archaic , Classical (c. 5th–4th centuries BC), and Hellenistic (c. 3rd century BC – 6th century AD) periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek. Its Hellenistic phase is known as Koine (&, begins with a distinction between precious and semi-precious stones; similar distinctions are made in other cultures. In modern usage the precious stones are diamond In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions. Diamond is renowned as a material with superlative, ruby A ruby is a pink to blood-red gemstone, a variety of the mineral corundum . The red color is caused mainly by the presence of the element chromium. Its name comes from ruber, Latin for red. Other varieties of gem-quality corundum are called sapphires. The ruby is considered one of the four precious stones, together with the sapphire, the emerald,, sapphire Sapphires are commonly worn as jewellery. Sapphires can be found naturally, by searching through certain sediments or rock formations, or they can be manufactured for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires , sapphires are used in some non-ornamental applications, including and emerald Emeralds are a variety of the mineral beryl (Be3Al26) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the 10 point Mohs scale of mineral hardness. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor, with all other gemstones being semi-precious.^[2] This distinction is unscientific and reflects the rarity of the respective stones in ancient times, as well as their quality: all are translucent In the field of optics, transparency is the physical property of allowing light to pass through a material; translucency (also called translucence or translucidity) only allows light to pass through diffusely. The opposite property is opacity. Transparent materials are clear, while translucent ones cannot be seen through clearly with fine color in their purest forms, except for the colorless diamond, and very hard,^[3] with hardnesses of 8-10 on the Mohs scale The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science. The method of comparing hardness by seeing which. Other stones are classified by their color, translucency and hardness. The traditional distinction does not necessarily reflect modern values, for example, while garnets The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name "garnet" may come from either the Middle English word gernet meaning 'dark red', or the Latin granatus , possibly a reference to the Punica granatum ("pomegranate"), a plant with red seeds similar in shape, are relatively inexpensive, a green garnet called Tsavorite Tsavorite or tsavolite is a variety of the garnet group species grossular, a calcium-aluminium garnet with the formula Ca3Al2Si3O12. Trace amounts of vanadium or chromium provide the green color, can be far more valuable than a mid-quality emerald.^[4] Another unscientific term for semi-precious gemstones used in art history Art history has historically been understood as the academic study of objects of art in their historical development and stylistic contexts, i.e. genre, design, format, and look. This includes the "major" arts of painting, sculpture, and architecture as well as the "minor" arts of ceramics, furniture, and other decorative and archaeology Archaeology, or archeology , is the study of past human societies, primarily through the recovery and analysis of the material culture and environmental data which they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes. Due to the fact that archaeology employs a wide range of different procedures, it can be is hardstone Hardstone is an unscientific term, mostly encountered in the decorative arts or archaeology, that has a similar meaning to semi-precious stones, or gemstones. Very hard building stones, such as granite, are not included in the term in this sense; only stones which are fairly hard, and regarded as attractive - in effect ones which could be used in. Use of the terms 'precious' and 'semi-precious' in a commercial context is, arguably, misleading in that it deceptively implies certain stones are intrinsically more valuable than others, which is not the case.

In modern times gemstones are identified by gemologists Gemology or gemmology is the science dealing with natural and artificial gems and gemstones. It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems, who describe gems and their characteristics using technical terminology Technical terminology is the specialized vocabulary of any field, not just technical fields. The same is true of the synonyms technical terms, terms of art, shop talk and words of art, which do not necessarily refer to technology or art. Within one or more fields, these terms have one or more specific meanings that are not necessarily the same as specific to the field of gemology Gemology or gemmology is the science dealing with natural and artificial gems and gemstones. It is considered a geoscience and a branch of mineralogy. Some jewelers are academically trained gemologists and are qualified to identify and evaluate gems. The first characteristic a gemologist uses to identify a gemstone is its chemical composition In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms of each element present in a compound. An empirical formula makes no reference to isomerism, structure, or absolute number of atoms. The empirical formula is used as standard for most ionic compounds, such as CaCl2, and for macromolecules, such. For example, diamonds are made of carbon Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of (C) and rubies of aluminium Aluminium (UK: /ˌæljʉˈmɪniəm/ AL-yew-MIN-ee-əm) or aluminum (US: /əˈluːmɨnəm/ ( listen) ə-LOO-mi-nəm) is a silvery white member of the boron group of chemical elements. It has the symbol Al and its atomic number is 13. It is not soluble in water under normal circumstances. Aluminium is the most abundant metal in the Earth's crust, oxide (Al₂O₃). Next, many gems are crystals which are classified by their crystal system In crystallography, a crystal system or crystal family or lattice system is one of several classes of space groups, lattices, point groups, or crystals. Informally, two crystals tend to be in the same crystal system if they have similar symmetries, though there are many exceptions to this such as cubic The cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals or trigonal In crystallography, the trigonal crystal system is one of the seven crystal systems, and the rhombohedral lattice system is one of the seven lattice systems. They are often confused with each other: crystals in the rhombohedral lattice system are always in the trigonal crystal system, but some crystals such as quartz are in the trigonal crystal or monoclinic In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. They form a rectangular prism with a parallelogram as its base. Hence two pairs of vectors are. Another term used is habit The many terms used by mineralogists to describe crystal habits are useful in communicating what specimens of a particular mineral often look like. Recognizing numerous habits helps a mineralogist to identify a large number of minerals. Some habits are distinctive of certain minerals, although most minerals exhibit many differing habits . Crystal, 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 Corundum is a crystalline form of aluminium oxide with traces of iron, titanium and chromium. It is a rock-forming mineral. It is one of the naturally clear transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, called ruby if red, while all other colors are called sapphire, while any other color of corundum is considered sapphire. Emerald Emeralds are a variety of the mineral beryl (Be3Al26) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the 10 point Mohs scale of mineral hardness. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor (green), aquamarine (blue), red beryl (red), goshenite The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al26. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, red, and white (colorless), heliodor The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al26. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, red, and white (yellow), and morganite The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al26. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, red, and white (pink) are all varieties of the mineral species beryl The mineral beryl is a beryllium aluminium cyclosilicate with the chemical formula Be3Al26. The hexagonal crystals of beryl may be very small or range to several meters in size. Terminated crystals are relatively rare. Pure beryl is colorless, but it is frequently tinted by impurities; possible colors are green, blue, yellow, red, and white.

Gems are characterized in terms of refractive index The refractive index or index of refraction of a substance is a measure of the speed of light in that substance. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium.[note 1] The velocity at which light travels in vacuum is a physical constant, and the fastest speed at which energy or information can, dispersion In optics, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency, or alternatively when the group velocity depends on the frequency. Media having such a property are termed dispersive media. Dispersion is sometimes called chromatic dispersion to emphasize its wavelength-dependent nature, or group-velocity, specific gravity Relative density, or specific gravity, is the ratio of the density of a substance to the density of a given reference material. Specific gravity usually means relative density with respect to water. The term "relative density" is often preferred in modern scientific usage, hardness The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science. The method of comparing hardness by seeing which, cleavage Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite crystallographic structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the microscope and to the naked eye, fracture The word fracture is often applied to bones of living creatures, or to crystals or crystalline materials, such as gemstones or metal. Sometimes, in crystalline materials, individual crystals fracture without the body actually separating into two or more pieces. Depending on the substance which is fractured, a fracture reduces strength or inhibits, and luster Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. For example, a diamond is said to have an adamantine lustre and pyrite is said to have a metallic lustre. The term is also used to describe other items with a particular sheen (for example, fabric, especially silk and satin, or metals). They may exhibit pleochroism Pleochroism is an optical phenomenon in which mineral grains within a rock appear to be different colors when observed at different angles under a polarizing petrographic microscope or double refraction Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain types of material, such as calcite crystals or boron nitride, depending on the polarization of the light. This effect can occur only if the structure of the material is anisotropic (directionally dependent). If the material has. They may have luminescence and a distinctive absorption spectrum.

Material or flaws within a stone may be present as inclusions.

Gemstones may also be classified in terms of their "water". This is a recognized grading of the gem's luster and/or transparency and/or "brilliance".^[5] Very transparent gems are considered "first water", while "second" or "third water" gems are those of a lesser transparency.^[6]

Value of gemstones

There are no universally accepted grading systems for any gemstone other than white (colorless) diamond. 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).^[7]

A mnemonic device, the "four C's" (color, cut, clarity and carat), has been introduced to help the consumer understand the factors used to grade a diamond.^[8] With modification these categories can be useful in understanding the grading of all gemstones. The four criteria carry different weight depending upon whether they are applied to colored gemstones or to colorless diamond. In diamonds, cut is the primary determinant of value followed by clarity and color. Diamonds are meant to 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, it is the purity and beauty of that color that 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, and asteria (star effects). The Greeks for example greatly valued asteria in gemstones, which were regarded as a powerful love charm, and Helen of Troy was known to have worn star-corundum.^[9]

Historically gemstones were classified into precious stones and semi-precious stones. Because such a definition can change over time and vary with culture, it has always been a difficult matter to determine what constitutes precious stones.^[10]

Aside from the diamond, the ruby, sapphire, emerald, pearl (strictly speaking not a gemstone) and opal^[10] have also been considered to be precious. 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 have been popular and hence been regarded as precious.

Nowadays such a distinction is no longer made by the trade.^[11] 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 meant to include those gemstones which occur so infrequently in gem quality that they are scarcely known except to connoisseurs, include andalusite, axinite, cassiterite, clinohumite and red beryl.

Gem prices can fluctuate heavily (such as those of tanzanite over the years) or can be quite stable (such as those of diamonds). In general per carat prices of larger stones are higher than those of smaller stones, but popularity of certain sizes of stone can affect prices. Typically prices can range from 1USD/carat for a normal amethyst to 20,000-50,000USD for a collector's three carat pigeon-blood almost "perfect" ruby.

Grading

In the last two decades there has been a proliferation of certification for gemstones. There are a number of^[11] laboratories which grade and provide reports on diamonds. As there is no universally accepted grading system for colored gemstones, only one laboratory, AGL (see below) grades gemstones for quality using a proprietary system developed by the lab.

• International Gemological Institute (IGI), independent laboratory for grading and evaluation of diamonds, jewellery and colored stones.
• Gemological Institute of America (GIA), the main provider of education services and diamond grading reports
• American Gemological Society (AGS) is not as widely recognized nor as old as the GIA.
• American Gem Trade Laboratory which is part of the American Gem Trade Association (AGTA) a trade organization of jewelers and dealers of colored stones.
• American Gemological Laboratories (AGL) which has been taken over by "Collector's Universe" a NASDAQ listed company which specializes in certification of collectables such as coins and stamps
• European Gemological Laboratory (EGL) founded in 1974 by Guy Margel in Belgium.
• Gemmological Association of All Japan (GAAJ-ZENHOKYO), Zenhokyo, Japan, active in gemological research
• Gemmological Institute of Thailand (GIT) is closely related to Chulalongkorn University
• Gemmology Institute of Southern Africa, Africa's premium gem laboratory.
• Asian Institute of Gemmological Sciences (AIGS), the oldest gemological institute in South East Asia, involved in gemological education and gem testing
• Swiss Gemmological Institute (SSEF), founded by Prof. Henry Hänni, focusing on colored gemstones and the identification of natural pearls
• Gübelin Gem Lab, the traditional Swiss lab founded by the famous Dr. Eduard Gübelin. Their reports are widely considered as the ultimate judgement on high-end pearls, colored gemstones and diamonds

Each laboratory has its own methodology to evaluate gemstones. Consequently a stone can be called "pink" by one lab while another lab calls it "Padparadscha". One lab can conclude a stone is untreated, while another lab concludes that it is heat treated.^[11] To minimise such differences, seven of the most respected labs, i.e. AGTA-GTL (New York), CISGEM (Milano), GAAJ-ZENHOKYO (Tokyo), GIA (Carlsbad), GIT (Bangkok), Gübelin (Lucerne) and SSEF (Basel), have established the Laboratory Manual Harmonisation Committee (LMHC), aiming at the standardization of wording on reports and certain analytical methods and interpretation of results. Country of origin has sometimes been difficult to find agreement on due to the constant discovery of new locations. Moreover determining a "country of origin" is much more difficult than determining other aspects of a gem (such as cut, clarity etc.).^[12]

Gem dealers are aware of the differences between gem laboratories and will make use of the discrepancies to obtain the best possible certificate.^[11]

Cutting and polishing

A few gemstones are used as gems in the crystal or other form in which they are found. Most however, are cut and polished for usage as jewelry. The picture to the left is of a rural, commercial cutting operation in Thailand. This small factory cuts thousands of carats of sapphire annually. The two main classifications are stones cut as smooth, dome shaped stones called cabochons, and stones which are cut with a faceting machine by polishing small flat windows called facets at regular intervals at exact angles.

Stones which are opaque such as opal, turquoise, variscite, etc. are commonly cut as cabochons. These gems are designed to show the stone's color or surface properties as in opal and star sapphires. Grinding wheels and polishing agents are used to grind, shape and polish the smooth dome shape of the stones.^[13]

Gems which are transparent are normally faceted, a method which shows the optical properties of the stone’s interior to its best advantage by maximizing reflected light which is perceived by the viewer as sparkle. There are many commonly used shapes for faceted stones. The facets must be cut at the proper angles, which varies depending on the optical properties of the gem. If the angles are too steep or too shallow, the light will pass through and not be reflected back toward the viewer. The faceting machine is used to hold the stone onto a flat lap for cutting and polishing the flat facets.^[14] Rarely, some cutters use special curved laps to cut and polish curved facets.

Gemstone color

Color is the most obvious and attractive feature of gemstones. The color of any material is due to the nature of light itself. Daylight, often called white light, is actually a mixture of different colors of light. When light passes through a material, some of the light may be absorbed, while the rest passes through. The part that is not absorbed reaches the eye as white light minus the absorbed colors. A ruby appears red because it absorbs all the other colors of white light (blue, yellow, green, etc.) except red.

The same material can exhibit different colors. For example ruby and sapphire have the same chemical composition (both are corundum) but exhibit different colors. Even the same gemstone can occur in many different colors: sapphires show different shades of blue and pink and "fancy sapphires" exhibit a whole range of other colors from yellow to orange-pink, the latter called "Padparadscha sapphire".

This difference in color is based on the atomic structure of the stone. Although the different stones formally have the same chemical composition, they are not exactly the same. Every now and then an atom is replaced by a completely different atom (and this could be as few as one in a million atoms). These so called impurities are sufficient to absorb certain colors and leave the other colors unaffected.

For example, beryl, which is colorless in its pure mineral form, becomes emerald with chromium impurities. If you add manganese instead of chromium, beryl becomes pink morganite. With iron, it becomes aquamarine.

Some gemstone treatments make use of the fact that these impurities can be "manipulated", thus changing the color of the gem.

Treatments applied to gemstones

Gemstones are often treated to enhance the color or clarity of the stone. Depending on the type and extent of treatment, they can affect the value of the stone. Some treatments are used widely because the resulting gem is stable, while others are not accepted most commonly because the gem color is unstable and may revert to the original tone.^[15]

Heat

Heat can improve gemstone color or clarity. The heating process has been well known to gem miners and cutters for centuries, and in many stone types heating is a common practice. Most citrine is made by heating amethyst, and partial heating with a strong gradient results in ametrine - a stone partly amethyst and partly citrine. Much aquamarine is heated to remove yellow tones and change the green color into the more desirable blue or enhance its existing blue color to a purer blue.^[16]

Nearly all tanzanite is heated at low temperatures to remove brown undertones and give a more desirable blue/purple color. A considerable portion of all sapphire and ruby is treated with a variety of heat treatments to improve both color and clarity.

When jewelry containing diamonds is heated (for repairs) the diamond should be protected with boracic acid; otherwise the diamond (which is pure carbon) could be burned on the surface or even burned completely up. When jewelry containing sapphires or rubies is heated, it should not be coated with boracic acid or any other substance, as this can etch the surface; they do not have to be "protected" like a diamond.

Radiation

Virtually all blue topaz, both the lighter and the darker blue shades such as "London" blue, has been irradiated to change the color from white to blue. Most greened quartz (Oro Verde) is also irradiated to achieve the yellow-green color.

Waxing/oiling

Emeralds containing natural fissures are sometimes filled with wax or oil to disguise them. This wax or oil is also colored to make the emerald appear of better color as well as clarity. Turquoise is also commonly treated in a similar manner.

Fracture filling

Fracture filling has been in use with different gemstones such as diamonds, emeralds and sapphires. In 2006 "glass filled rubies" received publicity. Rubies over 10 carat (2 g) with large fractures were filled with lead glass, thus dramatically improving the appearance (of larger rubies in particular). Such treatments are fairly easy to detect.

Synthetic and artificial gemstones

Some gemstones are manufactured to imitate other gemstones. For example, cubic zirconia is a synthetic diamond simulant composed of zirconium oxide. Moissanite is another example. The imitations copy the look and color of the real stone but possess neither their chemical nor physical characteristics. Moissanite actually has a higher refractive index than diamond and when presented beside an equivalently sized and cut diamond will have more "fire" than the diamond.

However, lab created gemstones are not imitations. For example, diamonds, ruby, sapphires and emeralds have been manufactured in labs to possess identical chemical and physical characteristics to the naturally occurring variety. Synthetic (lab created) corundums, including ruby and sapphire, are very common and they cost only a fraction of the natural stones. Smaller synthetic diamonds have been manufactured in large quantities as industrial abrasives.

Whether a gemstone is a natural stone or a lab-created (synthetic) stone, the characteristics of each are the same. Lab-created stones tend to have a more vivid color to them, as impurities are not present in a lab, so therefore do not affect the clarity or color of the stone.

Hybrid gemstones

The terms synthetic, natural, artificial, and imitation are well-understood by gemologists. However, gemologists have had to continually explain these terms, as applied in gemology, both to those within and outside of the industry, as synthetic in particular has different definitions when applied to different fields.

It is precisely because certain new gem treatments overlap more than one gem category that the term hybrid has been suggested. These materials consist of an original natural material that has been significantly added to – to the extent that the term natural no longer applies. Hybrid gems consist of natural material along with artificial material – either synthetic growth or polymers or glasses.

Hybrid is defined as those gem materials where there is no easy means of separating the natural from the artificial components. This is key, in that with a doublet or a triplet, the natural material can be isolated, identified – and theoretically retrieved from the whole. Hybrid will not be confused with assembled, but it will encompass reconstructed materials as well as B-jades.

Hybrid will not apply to traditional oiling of emerald and (comparatively minor) fracture healing as seen in many Mong Hsu rubies; these treatments are insignificant in comparison and additives would account for less than 5% of the total mass in most cases, but there remains the possibility that some heavily treated stones in these categories may qualify as hybrids.

Major industry educators, dealers, and trade organizations have seen the need for this new upper-level category. In some ways it is a dramatic addition to the gemological terms, but is merely a natural evolution due to modern treatment methods.

Notes

1. ^ The Oxford Dictionary Online and Webster Online Dictionary
2. ^ Precious Stones, Max Bauer, p 2
3. ^ Precious Gemstone glossary of Jewelry
4. ^ Wise, R. W., 2006, Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones, Brunswick House Pr, pp.3-8 ISBN 0972822380
5. ^ AskOxford.com Concise Oxford English dictionary online.
6. ^ Desirable diamonds: The world's most famous gem. by Sarah Todd.
7. ^ Wise, R. W., 2006, Secrets of The Gem Trade, The Connoisseur's Guide To Precious Gemstones, Brunswick House Pr, p.36 ISBN 0972822380
8. ^ Wise, R. W., 2006, Secrets Of The Gem Trade, The Connoisseur's Guide To Precious Gemstones, Brunswick House Pr, p. 15
9. ^ Burnham, S.M. (1868). Precious Stones in Nature, Art and Literature. Bradlee Whidden. Page 251
10. ^ ^{a b} Church, A.H. (Professor at Royal Academy of Arts in London) (1905). Precious Stones considered in their scientific and artistic relations. His Majesty's Stationary Office, Wyman & Sons. Chapter 1, Page 9: Definition of Precious Stones URL: Definition of Precious Stones
11. ^ ^{a b c d} Secrets of the Gem Trade; The Connoisseur's Guide to Precious Gemstones Richard W Wise, Brunswick House Press, Lenox, Massachutes., 2003
12. ^ "Rapaport report of ICA Gemstone Conferene in Dubai". Diamonds.net. 2007-05-16. http://www.diamonds.net/news/NewsItem.aspx?ArticleID=17766. Retrieved 2010-07-30.
13. ^ Introduction to Lapidary by Pansy D. Kraus
14. ^ Faceting For Amateurs by Glen and Martha Vargas
15. ^ Gemstone Enhancement: History, Science and State of the Art by Kurt Nassau
16. ^ Nassau, Kurt (1994). Gem Enhancements. Butterworth Heineman.

External links

• International Gem Society
• Gemological Institute of America

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