The characteristic color that is determined by its wavelength as red, green, blue, purple, yellow, etc., and excludes white, black, and shades of gray in reference to the visible spectrum of light.
To result something of a genuine article or natural gemstone or simulate it from any material that imitate by its color, the appearance of a natural gemstone. Imitation gemstone having wholly different physical properties and chemical composition, and hen
The emission of light by a substance due to high temperatures: white or bright-red heat. When objects such as iron placed in fire it become dull red by 700 C degree. From 700 C degree to 1500 C degree, the color shifted from red to orange and definitely y
The chrysoberyl crystal is penetrated by microscopic tubes, two-phase or relatively short needles parallel to the vertical or c-axis of the crystal, suitable for cut en cabochon. In brown and yellow varieties can be seen. The so-called stepped twin planes
A general name for any small visible foreign matter such as gas, liquid, glass, or mineral enclosed within a gemstone or rock, which is a growth phenomena. Fracture or cleavage in a gemstone are not classed as inclusions. The nature of inclusions are used
In crystal optics, a number indicating the speed of the velocity of light in a vacuum or air to its velocity in a given crystal. The refractive index (RI) of a crystal can be expressed as ratio of the sine of the angle of incidence to the sine of the angl
The process of exposing certain diamond or other pale or poorly colored gemstone to radiation, such as in nuclear reactor, X-rays, neutrons from an atomic pile, deuterons a nucleus of the heavy hydrogen atom, gamma rays from a cobalt-60, electrons positiv
A number of decorative articles made artistically of gold, platinum, silver, and precious stones that are worn for personal adornment, such as bracelets, rings, necklaces, etc.
Indian gem lore was from ancient times famous for its good quality and richness. There are several famous gems in other museums such as Timur Ruby, Koh-i-Nur Diamond, etc. Most famous part of Indian jewels was in possession oh Maharajah Duleep Singh.
In metallurgy a unit that expresses only to the purity of solid gold used in jewelry. In trade based on a scale of twenty-fourths, 24 karat means pure gold, 18 karat gold means, containing 18 parts gold to 6 parts of alloy, and 9 karat gold means, contain
An acronym of light amplification by stimulated emission of radiation. A device that emits UV to infra red electromagnetic energy, that is a nearly parallel, nearly monochromatic and coherent beam of light of very restricted diameter formed by causing exi
In optics, the reduction of the light intensity in transmission through an absorbing substance or in reflection from a surface, in crystals, minerals and gems. Absorption may vary with wavelengths of vibration in the direction of the transmitted light or
The emission of certain visible wavelengths of light from a substance other than thermal process, which are used as diagnostic determination of gemstones. It is caused by the emission of photons, when an exited atom within the substance returns to the gro
A naturally occurring molten or semi-molten material in suspension, with dissolved gases, generated within or beneath the earth's crust and capable of intrusion and extrusion. Magma, which is extruded on the surface of the earth is called lava.
Any rock, which has been derived from pre-existing rocks by mineralogical, chemical composition, textural and structural changing, essentially in the solid state due to processes operating in the earth's crust of heat or intense pressure, shearing stress,
A loose and inexact term that may be to define: usually homogeneous inorganic substance of definite physical properties and more or less chemical composition, which occur naturally in the earth, and usually possess a crystalline structure, which frequentl
The scientific study of minerals; their formation, occurrence, chemical composition, physical properties, and their classification. Oryctognosy and oryctology are obsolete terms.
The most commonly used ten standard scale of relative hardness of minerals. The scale is expressed in numbers ranging from 1 through 10: (1) talc, (2) gypsum, (3) calcite, (4) fluorite, (5) apatite, (6) orthoclase, (7) quartz, (8) topaz, (9) corundum, (10
Testing a gemstone on a refractometer prism, when the stone has a greater refractive index than the measuring prism of the device, or higher than the refractive index of immersion liquid used for optical contact, the scale of refractometer remains dark an
Synthetic alexandrite made in three methods in Russia, (a) growing synthetic stones of solution-growth process or flux process specially for alexandrite, (b) Growing stone of floating-zone process. (c) Melt-grown process or so-called pulling method.
The placing of atoms or radicals in a crystal so that they point in a definite direction, or its crystallographic axes are in the conventional position.
A light-colored, coarse-grained igneous rock from granite clan containing orthoclase, quartz, microline, mica, gemstones, and many ferromagnesian minerals resulting from slow solidification. Pegmatite is occurring place of many uncommon gem minerals such
Prized by collectors. Synthetic strontium titanate or fabulite found in a similar manner to perovskite. Natural counterpart of fabulite with the same composition is called tausonite.
The sum of homogeneous, physically distinct portion of matter in heterogeneous system, as the three phases; solid, liquid, or gas. Each phase may exist in different temperatures and pressures.
A special optical occurrence, or circumstance observed or are visible in certain gemstones such as chatoyancy, asterism, or play of color, adularescence, girasol, labradorescence, opalescence, schiller, etc.
Physical properties of gemstones are extremely important in understanding geological phenomena in synthesizing new materials, and identification of minerals. Physical properties and chemical composition of minerals change with temperature and pressure. P
Quantum of light or electromagnetic radiation, it can behave as a wave or as a particle. Traveling at the velocity of light. Photon have momentum but not mass or electrical charge. Also known as light quantum. Caused by excitation of atoms and molecules a
A variety of translucent, grayish-green to greenish yellow chatoyant quartz or chalcedony containing fine parallel fibers of asbestos or parallel channels, arranged through the stone at right angles to the eye and parallel to the base of the crystal, that
An unusual feature occur in Verneuil synthetic corundum by plunging of still heated stone into a much cooler liquid (thermal shock), which create fractures and it resemble closely to natural stone. By pursuing of this process developed honeycomb pattern d
An oily colorless, specific odor, insoluble, basic heterocyclic with the formula C9H7N. Composed synthetically by heating aniline, nitrobenzene, glycerol, and sulfuric acid. Used as food preservative and in the manufacture of dyes and antiseptics. R.I. -
The four quadrilateral facets of 8 main facets on the crown or on the pavilion of a brilliant-cut stone, which are also called bezel facets. The 4 on the crown touching the girdle with their apex and extending up to touch the table. There are four lozenge
The emission of particles or electromagnetic waves from a source such as nuclear radiation, X-rays, neutrons, gamma rays, electrons positive or negative, protons. Radiation has the effect of artificially altering color by artificially creating color cent
Radium treatment of minerals such as beryl to produce a bluish-white fluorescence only on the basal planes. Under SWUV and LWUV light beryl fluoresces bluish-white.
The turning back of wave from surface, on which they are incident according to the definite law of reflection. A small part of ray 17.2% of incident light striking the surface vertically is reflected from the surface (the 17.2% is upper limit of reflected
Several methods are available for the measurement of refractive indices such as refractometer for total reflection, immersion method in liquid for Beck effect, shadow method, and minimum deviation method.
Dioxide of silicon (SiO2), which appeared in five crystalline polymorphous such as quartz (alpha and beta), tridymite, cristobalite, coesite, and stichovite, in cryptocrystalline such as chalcedony and chert, and in amorphous such as opal (a hydrated sili
To simulate or imitate a natural gemstone, which is made from components that are easier, cheaper or more convenient to manufacture. Simulated stone having superficial appearance to the true stone but differs from it either in chemical composition, struct
The ratio of the weight of any substance to that of pure water at temperature of 3.98 C (39.2 F) degree and standard atmospheric pressure. Specific gravity of gems and minerals are determined by means by hydrostatic weighing method.
A small hand optical device for obtaining and visually observing spectrum, in which collimated light passes through a narrow slit onto either a prism or diffraction grating, its spectrum being viewed by a lens system or telescope. The angle between the c
Any array of electromagnetic visible light ordered according to its constituent wavelengths or colors, when the white light is dispersed by a prism or diffraction grating, ranging from about 750 to about 400 nm. The spectra can obtained by means of spectr
An isomorphous mineral of spinel group. A wide range of colors and shade of gemstone. Red-orange is named as flame spinel, an iron-rich dark-green to black, which is known as green spinel, pleonaste or ceylonite, grass-green as chlorospinel (iron-rich), b
Artificially made substance that has the same appearance, physical properties and chemical compound as its natural counterpart mineral. Some synthetic stones have no counterpart in nature they are synthetic gemstones except if they used as an imitation fo
A misleading term for synthetic spinel or corundum (sapphire), which is able to change color like alexandrite reddish-green in daylight and reddish at artificially light, such stones were at first misnomered as scientific alexandrite. Synthetic sapphire
The science of high temperature of one subject to change its color, because by increasing of temperature expands the bond length of lattice, reduced the ligand field. A red compound of 10% Cr2O3 and 90% Al2O3 by increasing the temperature to over 400 C th
A variety of luminescence where certain rocks of minerals showing the property due to application of heat or infrared. Some diamonds exhibits blue thermoluminescence, when heated to about 200 C. Thermoluminescence emitted when the color traps are disappea
A gemstone permits the pass of electromagnetic radiation through it without distortion so that the object can be seen clearly and distinctive through it, such a quartz crystal. It is a see through effects.
A type of igneous rock characterized by a high content of mafic minerals, particularly olivine, pyroxenes, amphiboles, etc. The silica content is less than 45%.
A device for cleaning dirt and other foreign particles from gemstones and jewelry articles by subjecting them to ultrasonic vibrations immersed in water or other solvent. The articles must be free of stress flaws. Glass lenses and other bodies can be poli
A mercury discharched lamp in quartz glass designed to produce ultraviolet light for exciting luminescence in gem minerals specially diamonds. The long-wave lamp is provided with wood's glass filter to emit wavelengths between 400 nm and 300 nm. To obtain
A special magnifying device for investigating the objects are illuminated by ultraviolet light in the range 180 to 400 nm. The resolving power is increased corresponding to the resolution of shorter wavelengths than visible light. It requires special quar
A miniature cathode ray tube (CRT), which is closet to cover glass and heated cathode made of tungsten wire emits electrons. The electrons are accelerated by positively charged by hexagonal steel and passing through the grid to anodes covered with blue fl
A very hard, light-gray, ductile, malleable, metallic element of the group V of the Periodic System with the symbol V. It is one of the 8 pigment metals responsible for color in gemstones such as beryl, sapphire (natural or synthetic). Used as a component
A solid volcanic natural form of glass (rock) produced by sudden cooling and solidification of viscous lava before crystallization can take place, such as obsidian, pitchstone or other glassy masses. Obsidian is used for tumbled gems, ornamental objects,
Generally a fine crystalline or glassy igneous rock, which is formed by the solidification of molten magma or lava on the Earth's surface during volcanic action. Such as basalt, obsidian, etc.
The distance between two points having the same phase on the following or preceding wave. The wavelength of electromagnetic radiation is equal to the velocity of the wave divided by its frequency =c/v. It is measured in nanometers unit.
A natural geological description for disintegration and decomposition of rocks and minerals as consequent exposure to atmospheric agents at or near the Earth's surface such as chemical action of air, rainwater, frost, insolation, bacteria, plants, and mec
The produced wavelengths of X-rays according to the electromagnetic theory of light consisting of continuous band of wavelengths, which are a mixture of all wavelengths. Depends on the used voltage of apparatus, which is know as white X-ray radiation or g
A device to obtain an X-ray spectrum for determining the wavelength of its chemical consistent. Each element, when irradiated by electrons, emits X-ray of several characteristic frequencies the line spectrum depending on the atomic number.
To generate monochromatic X-rays or line spectrums only one wavelength used is a suitable selective filter made of very thin layers of metal elements. There have one or two atomic numbers lower than the target metal such as nickel with atomic number 28 us
If a crystal is irradiated by an intense X-ray or gamma-ray beam, this includes the substance to emit its visible characteristic secondary X-ray line spectra of a longer wavelength, which is known as X-ray fluorescence. It is a nondestructive method. Used
Several characteristic lines of the spectrum of X-ray, which are emitted by a bombardment of material with electrons such as curved dark lines on the films produced by X-ray method of powder diffraction of stone or minerals.
A colorless glass-like material used as an impregnation or filling agent to improve the appearance and reduce the visibility of inclusions in stones such as diamonds and emeralds.