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Dutoitspruit PDF Print E-mail
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Tuesday, 18 September 2007

Dutoitspruit. A minor alluvial dia­mond deposit in the Potchefstroom area, Transvaal Province, Republic of South africa. Current production is inconsequential.

Dutra diamond. See presidente dutra


dyke. Same as dike

. Dynagem. Trade name for man-made strontium titanate.

Dysortville Diamond. The unofficial name for a 4.33-carat, fine-quality crystal that was discovered near Dysortville, McDowell Co., North Carolina in the 1870's. It later came into the possession of Tiffany & Co., who donated it to the J. Pierpont Morgan gem collection of the American Museum of Natural His­tory, New York City, from which it was stolen in 1964.

Dutch rose cut PDF Print E-mail
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Tuesday, 18 September 2007

Dutch rose cut. Sometimes known as the Holland rose or crowned rose. More pointed than other rose cuts. There are 24 triangular facets ar­ranged in groups of six over a flat base. The height is usually half the diameter of the stone. Du Toit I diamond. A 250-carat yel­lowish crystal found in the Du-toitspan Mine, Republic of South africa, in 1871. Present ownership unknown.

Du Toit II Diamond. A 127-carat yellowish crystal found in the Dutoitspan Mine, Republic of South Africa, in 1871. Present whereabouts unknown. Dutoitspan Diamond. See oppenheimer


Dutoitspan Mine (du-toits"-pahn).

The second diamond pipe mine dis

covered in South Africa (September, 1870), on the farm Dorstfontein, near the present town of Kimberley. Dutoitspan was the name given to the pan, or natural land basin, on this farm. This mine is noted for its large yellow Diamonds and for its production of a large proportion of big stones. Annual production is usually between 200,000 and 300,000 carats.

Last Updated ( Tuesday, 18 September 2007 )
Dudley Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Dudley diamond. See star of south

africa DIAMOND.

durability (of diamond). The durabil­ity of a gem depends both on its hardness and toughness. It may be quite tough but rather easily scratched, or it may be exceedingly hard but lack toughness because of easy cleavage. Diamond is highest on the scale of hardness, and despite its rather easily developed octahedral cleavage, it is among the toughest of Gemstones. See cleavage, cleavage (in


Dutch bort. A misnomer for zircons found in the South African diamond mines.

Dutch Guiana. See Surinam.

Droogpan PDF Print E-mail
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Tuesday, 18 September 2007

Droogpan. A small alluvial diamond deposit in the Ventersdorp area, Trans­vaal Province, Republic of South Af­rica. Total annual production is negligi­ble.

Droogveld Sluit. An ancient, gravel-filled fissure discovered at Droog­veld, Vaal River Estate, Republic of South africa, in 1912, that was a pro­lific producer of Diamonds. It was two miles long, about 100 feet wide, and from 20 to 40 feet deep. During the first 18 months after its discovery, the output totaled more than 77,000 carats, valued at £463,770. Total production for one recent year was less than 300 carats. drop cut. Any form of cutting suita­ble for use in pendants, earrings, etc. such as the briolette, or pear shape.

dry diggings. A term that refers to pipe diamond deposits, as opposed to alluvial, or wet, diggings.

ducat. A small, distorted octahedron on which one facet, the table, has

been polished. Originally called the Duke Cut; also known as "ducats," "ducuts" or merely "dukes."

Dresden White Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Dresden White diamond. Augustus the Strong of Saxony (1670-1733)

was a man of luxurious and ex­travagant tastes, especially where jewels, paintings and other art ob­jects were concerned. For example, he is reported to have paid between $750,000 and $1,000,000 for a single diamond that struck his fancy: a colorless, square-cut, 49.71-carat stone that came to be known as the Dresden (or Saxon) White. This probably would have been the high­est per carat price paid for a diamond at that time. Like its cele­brated companion, the Dresden Green, this historically important stone is mounted in an elaborate eighteenth-century shoulder knot (with 19 other large Diamonds and 216 other smaller rose-cut stones) and has long held a prominent place among the Crown Jewels of Saxony in the Green Vaults in Dresden, Germany. It, too, was confiscated by the Russians after World War II but is now back in its familiar resting place in Dresden's Historical Museum.

Dresden yellow diamond. Formerly in the famous Green Vaults of the State Art Collection in Dresden, Germany, this 38-carat, yellow, brilliant-cut diamond was confis-

cated by the Soviet Trophies' Or­ganization in 1945. In 1958, how­ever, it was returned to Dresden by the Russians and is again on display in the Museum.

Dresden Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Dresden diamond. See English Dres­den DIAMOND.

Dresden Drop Diamond. See English


Dresden Green Diamond. A signifi­cant apple-green 41-carat pear-shaped diamond. It is the largest existing his­torical diamond of this color and is set in an elaborate pendant-type mounting with several smaller Diamonds. The early history is un­known although it is believed of In­dian origin. The Dresden Creen first appeared at the Leipzig Fair of 1743 where it was purchased by Frederick Augustus II of Saxony for about $150,000. Until World War II the Dresden Creen was exhibited with other Crown Jewels of Saxony in the

Dowagiac Diamond PDF Print E-mail
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Tuesday, 18 September 2007

Dowagiac diamond. A 10.87-carat rounded, hexoctahedral crystal that was found in 1895 near Dowagiac, Cass Co., Michigan. Its present whereabouts is unknown.

drag line. Irregularities in polish caused by inclusions at the surface leaving a marking downstream from the object. Polishing drag lines are caused by polishing powder or mi­nute detritus being pulled from an inclusion or feather by the rotation of the lap. They are only seen on one side of the inclusion since they origi-

nate at the point where the inclusion reaches the surface.

draw color. When several Diamonds are placed in a diamond paper to­gether and light passes through one stone after another, each stone tends to intensify the slight color of the other. The group of stones is then said to draw color. The term is also used to describe an individual dia­mond with a visibly yellow body color.

doublet PDF Print E-mail
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Tuesday, 18 September 2007

doublet. A composite assembled stone usually of two parts, crown and pavilion, cemented or fused

together. diamond doublet has a diamond top and pavilion of syn­thetic colorless sapphire or spinel, quartz, glass, or rarely diamond; usually is closed set. Other simulants include doublets of almandine garnet tops with glass pavilions, or synthetic colorless sapphire or spinel crowns and strontium titanate bottoms. See


double-Holland rose cut PDF Print E-mail
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Tuesday, 18 September 2007

double-Holland rose cut. An alter­nate name for double-Dutch rose cut.

double refraction. See anisotropic double rose cut. A rarely used rose style of cutting that consists of two full-Dutch rose cuts, base to base, thus resulting in a circular-girdled stone without a table or culet and having a total of 48 triangular facets.

double-Dutch PDF Print E-mail
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Tuesday, 18 September 2007

double-Dutch (or double-Holland) rose cut. A rarely used rose style of cutting that has a circular girdle out­line, a flat, unfaceted base and a pointed, dome-shaped crown bear­ing 36 triangular facets.

doubleering. A term of Dutch origin, meaning an iridescent flaw; an ex­tension within a diamond of an ex­ternal break. Also means a "gletz"

dop marks PDF Print E-mail
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Tuesday, 18 September 2007
dop marks. Burn marks left on the surface of a diamond by the "fin¬gers" of a mechanical dop. double bevel cut. See BEVEL CUT double-color diamond. A little-used term that refers to a diamond that is one color under artificial (incandes¬cent) light and another color in day¬light, due to strong fluorescence. A technical term for this color change is fluorochromatic. See FLUORESCENCE, FLUOROCHROMATIC, PREMIER DIAMOND, TRANS-ICHROMATIC double-cut brilliant. A rarely used style of brilliant cutting that has a total of 34 facets: four main facets and 12 break facets on both crown and pavilion, plus a table and a culet.
Doelter PDF Print E-mail
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Tuesday, 18 September 2007

Doelter, C. A German scientist who, about 1902, attempted to produce synthetic Diamonds by the Friedlan-der method but with more complex mixtures. See friedlander, l, synthetic diamond.

Doornbult. A minor alluvial diamond deposit in Wolmaransstad area, Transvaal Province, Republic of South africa. This mine contributes very little to total South African allu­vial production.

Doornkloof. (1) One of the more im­portant alluvial diamond deposits in

the Barkly West area, Cape Province, Republic of South Africa. Production for one recent year totaled approxi­mately 11,000 carats. (2) Also, the name of a small pipe mine in the same area, owned by Treasure Trove Diamonds, Ltd.

Doornlaagte. A minor alluvial dia­mond deposit in the Barkly West area, Cape Province, Republic of South Africa. Current production is negligible.

dop. Any device that is used to hold a diamond during the sawing or faceting process. One type of dop consists of a metal cup on the end of a flexible rod that is filled with a low-melting-point lead alloy in which the rough diamond is held. Another type, called a mechanical dop, is a small adjustable vise that holds the diamond at the proper angle on the polishing wheel, or lap. Although the shellac-and-wax holder for both diamonds to be cleaved and for the sharp used to groove dia­monds preparatory to cleaving is usu­ally called a cleaver's stick. It, too, is sometimes called a dop. A cutter's

dispersion PDF Print E-mail
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Tuesday, 18 September 2007

dispersion. The property of transpa­rent Gemstones to separate white light into the spectral colors. The interval between such colors varies in different gemstones, and is usually expressed by the measure of the dif­ference between the refractive indi­ces of the red ray and the violet ray. diamond has the highest dispersion (.044) of any of the popular, natural, colorless gems. See fraunhofer lines.

Di'Yag. Trade name for man-made yttrium aluminum garnet (YAC). Djevalite. Trade name for man-made cubic zirconia.

dodecahedral cleavage (doe'-dek-ah-he"-dral). Cleavage in six planes, parallel to pairs of opposite faces

of the dodecahedron. Although dia­mond may show such cleavage, it is not easily developed. See dodeca­hedron, CLEAVAGE, CLEAVAGE (IN DIAMOND).

dodecahedron (doe'-dek-ah-he"-dron). One of the seven basic forms in the highest symmetry (hexoctahe-dral) class of the cubic, or isometric, crystal system. It has 12 rhomb-shaped faces, each of which inter­sects two of the crystallographic axes and is parallel to the third. It is also called the rhombic-dodecahedron. See cubic system, hexoctahedral class.

directional hardness PDF Print E-mail
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Tuesday, 18 September 2007

directional hardness. The relative hardness of diamond varies in dif­ferent directions. Because of dia­mond's covalent bonding which in­volves sharing of electrons, hard­ness is spatially directed. Thus hard­ness in diamond depends upon the number of bonds per unit area (bond density) and, therefore, varies with crystallographic direction. Conse­quently, the greater the number of chemical bonds in a given volume or direction, the harder is the mineral or directional property. The order of relative hardness in diamond from hardest to softest is: 1) cube 45° to axis; 2) dodecahedron 90° to axis; 3) octahedron towards cube; 4) oc­tahedron to dodecahedron; 5) cube parallel to crystal axis; 6) dodeca­hedron parallel to crystal axis. These

relative differences in hardness vary from about ten times to one hundred times; consequently the practical polishing directions are 5 and 6 above, since polishing against the lattice is harder than polishing with it. There is no soft direction on the oc­tahedral plane.

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Tuesday, 18 September 2007

DICORWAF. Abbreviation for diamond Corporation West africa, Ltd. Licensed exporter of Sierra Leone Diamonds and managing agents of GDO.

Dievedraai. A minor alluvial dia­mond deposit in the Schweizer Reneke area, Transvaal Province, Republic of South Africa. The present-day yield from this digging is negligible.

dike (or dyke). When a fissure cut­ting across the bedding planes of ear­lier rocks is filled by igneous rock, it is called a dike. Diamonds are some­times found in dikes of kimberlite. DIMINCO. See national diamond min­ing COMPANY (SIERRA LEONE), LTD.

diamond truer PDF Print E-mail
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Tuesday, 18 September 2007

diamond truer. A grinding-wheel truer consisting usually of a short steel rod inserted in a wooden handle and having in its free end an industrial diamond.

diamond turning tool. Any kind of a diamond dressing tool that contains a diamond lapped to a specific in­cluded angle and radius for use in turning operations.

diamond type. See type classification. diamond-washing cup. A perforated, solid-bronze cup, suspended inside of a glass jar with a glass cover, for washing and cleaning Diamonds and other Gemstones.

Diamond Winners' Association. One of the companies in Accra, Ghana, that is licensed by the government of that country to buy diamonds from native miners. See guana.

Diamond Yardstick. See master <or key)


Diamond-Yardstick Holder. A spe­cial device for holding master dia­monds in an elevated position in the

DiamondLite (trademark, Gemologi­cal Institute of America) to facilitate the color grading of mounted dia­monds. See color grade, diamondlite,


Diamone. Trade name for man-made yttrium aluminum garnet (YAG).

Diamonette. Trade name for synthet­ic sapphire.

Diamonflame. Trade name for syn­thetic sapphire.

Diamonique. Trade name for man-made yttrium aluminum garnet (YAG).

Diamonique I. Trade name for man-made YAG.

Diamonique II. Trade name for man-made GGG.

Diamonique III. Trade name for man-made cubic zirconia.

Diamonite. A trademarked name for synthetic rutile.

Diamonte. Trade name for man-made yttrium aluminum garnet (YAG).

Diamontina. Trade name for man-made strontium titanate.

Diamothyst. A trademarked name for synthetic rutile.

Diario De Minas Gerais Diamond. A

375.10-carat diamond that was found in the San Antonio River, Municipality of Coromandel, Minas Gerais, Brazil in 1941. The rough was purchased by Harry Winston in 1941 and cut into a number of gemstones. The present location of these stones is unknown. DICORP S.L. An abbreviation for Diamond Corporation (Sierra Leone), Ltd.

Diamond Throne PDF Print E-mail
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Tuesday, 18 September 2007

diamond Throne. In Buddhist legends, a throne that was supposed to have been made from a single diamond, 100 feet in circumference, that stood near the famous tree under which Buddha is said to have re­ceived enlightenment. When the whole world was shaken by storms and earthquakes, the throne was be­lieved to remain firm.

Diamond Trading Co., Ltd. The or­ganization that markets to the diamond trade the gem Diamonds it purchases from the Diamond Pur­chasing & Trading Co., Ltd.

Diamond Training Program, GIA.

See Appendix for a discussion of the Diamond Training Program offered by the Gemological Institute of America.

diamond setter PDF Print E-mail
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Tuesday, 18 September 2007
diamond setter. A person who pos¬sesses the training, experience, and skill to mount a fashioned diamond into items of jewelry using special equipment. See SETTER. diamond shovel. A small, stainless-steel shovel, with or without a han¬dle, used to facilitate the handling of large quantities of small Diamonds. diamond sieve. A round, perforated metal plate for rapid grading of loose, fashioned diamonds for size. A number of such plates are usually used, each having perforations of a different size. Diamond Syndicate. In the early days of the South African diamond fields, the word "syndicate" was used to refer to various groups of in¬dividuals and companies that held controlling interests in diamond pro¬duction and distribution. In 1893, a syndicate composed of 10 firms of¬fered to purchase all of the De Beers Company's diamonds. This seems to have been the embryo of the famous Diamond Syndicate that became so well known to jewelers in the early decades of the 20th Century as the price-fixing and market-controlling factor of the diamond industry. In various forms a diamond syndicate composed of different persons or firms functioned in this capacity until the crisis of 1929 demanded a mar¬keting organization of a more rigid type with greater capital. Although the term "syndicate" is no longer meaningful, it is often popularly applied to De Beers Consolidated Mines, Ltd., because it holds a con¬trolling interest in a number of diamond-mining companies and in companies that have buying con¬tracts with independent producers (including the Diamond Corporation Ltd.). See DE BEERS CONSOLIDATED MINES, LTD.
Diamond Research Laboratory PDF Print E-mail
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Tuesday, 18 September 2007

diamond Research Laboratory. A

scientific research organization es­tablished in 1947 in Johannesburg, Republic of South africa, and spon­sored by Industrial Distributors, Ltd. (a subsidiary of the Diamond Corpo­ration, Ltd.) for two principal pur­poses: (1) to assist mining companies with problems concerning extraction processes and in investigations lead­ing to increased output and reduced cost, and (2) to act as a research ser­vice center for all users of both in­dustrial and gem Diamonds. See


diamond saw. (1) A saw used for di­viding, or separating, diamonds (see sawing). (2) A diamond-charged blade used as a cutting edge in fash­ioning colored stones or in various applications in industry.

Diamondscope (trademark, Ameri­can Gem Society). A binocular gemological microscope incorporat­ing an especially designed illum­inator with an adjustable baffle that affords examination of diamonds and other Gemstones by either dark-or light-field illumination. It has the effect of eliminating most reflections from the crown facets, so the inclu­sions (imperfections) can be ob­served and identified. Used for both the identification of colored stones

Diamond Proportion Analyzer PDF Print E-mail
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diamond Proportion Analyzer. An eyepiece designed and manufactured by GIA for analyzing the proportions of round, brilliant-cut Diamonds and for determining new dimensions of stones to be recut. An accessory for zoom-type microscopes. It incorpo­rates a separate 15x Gemolite eye­piece, a diamond proportion reti­cle fitted inside the eyepiece, and a specially designed stoneholder with a magnetic base. When used with the Deluxe Mark V Gemolite the size range of stones that can be analyzed is 0.10 to 5.50 carats. Some fancy-cut diamonds may also be analyzed.

Diamond Purchasing & Trading Co., Ltd. A company that buys gem diamonds from the Diamond Pro­ducers' Association and from other African diamond sources. It sells them to the Diamond Trading Co., Ltd., for marketing to the world diamond trade.

Diamond Preserve of the United States PDF Print E-mail
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diamond Preserve of the United States, Inc. A company formed in the late 1940's for the purpose of per¬mitting the public to search for Diamonds in the Arkansas diamond deposits for a fee. The principal pipe is now owned by the State of Arkan¬sas and is advertised as the "Crater of Diamonds State Park." See ARKANSAS. Diamond Producers' Association. An association whose membership con¬sists of the Government of the Re¬public of South africa, the Adminis¬trator of the Mandated Territory of South-West Africa, De Beers Con¬solidated Mines, Ltd., Premier (Transvaal) Diamond Mining Co. (Pty.), Ltd., Consolidated Diamond Mines of South-West Africa (Pty.), Ltd., and the Diamond Corporation (Pty.), Ltd. It sells to the Diamond Purchasing & Trading Co. (Pty.), Ltd., and Industrial Distributors (1946), Ltd., all of the diamonds produced by its members. These companies have contracts with the Diamond Trading Co., Ltd., and Industrial Dis¬tributors (Sales), Ltd., for the market¬ing of all the diamonds acquired by them. Each of its members receives a quota of the world's diamond trade, after providing for the purchase by the Diamond Corporation of the out¬put of diamond producers who are not members.
diamond plow PDF Print E-mail
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Tuesday, 18 September 2007

diamond plow. A diamond-pointed tool for glass engraving.

diamond point. (1) A stylus tipped with diamond. (2) Same as point cut. diamond powder. Small particles of diamond that are used in loose form in industrial grinding, for fashioning the harder colored stones (e.g., ruby and sapphire), and for faceting and polishing Diamonds. It is also forced or molded into the surface of tools used for grinding, drilling, machin­ing, etc. Diamond grit and diamond dust are synonymous terms.

diamond paper PDF Print E-mail
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Tuesday, 18 September 2007

diamond paper. A sheet of paper folded to form a pocket in which Diamonds or other gems are con­tained. Usually, a durable paper stock is used. One or more sheets of similarly folded paper may be used to line and strengthen the outer paper. Weight, lot number, and coded or uncoded prices usually are marked on the flap of the paper.

diamond-paper weight. A collapsible frame, consisting of four hinged pieces of thin metal, used to hold diamond papers open while examin­ing stones.

diamond paste. A paste made of diamond powder and other suitable substances for use in grinding and pol­ishing purposes. A modern, high-grade diamond paste consists of a wetting and dispersing agent, a car­rier for maintaining a relatively per­manent and uniform suspension of the diamond particles, a plasticizer for attaining a desirable consistency of the carrier, and a dye or other col­oring agent to distinguish between different diamond grades.

diamond pencil. A cutting tool tipped with diamond used for cutting or marking.

diamond pipe. A cylindrical to ir­regular shaped, more or less vertical, diamond-bearing kimberlite intru­sion; an eruptive channel of a vol­canic breccia containing kimberlite. They usually decrease in area with increasing depth and contain suffi­cient diamonds to be minable. See


Diamond Manufacturers' Associa­tion PDF Print E-mail
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Tuesday, 18 September 2007

diamond Manufacturers' Associa­tion. The official organization of diamond manufacturers in England.

Diamond Manufacturers' Associa­tion of Puerto Rico. An organization of diamond-cutting ffrms in Puerto Rico.

Diamond Mining & Utility (S.W.A.), Ltd. The firm that holds the alluvial diamond-mining concession along the coast of South-West africa ad­jacent to that of Consolidated Diamond Mines of South-West Af­rica, Ltd. It extends north from 26° south latitude to the Tropic of Cap­ricorn. The concession is worked by Industrial Diamonds of South Africa (1945), Ltd. See south-west africa. diamond mortar. A small steel mor­tar used for pulverizing diamond for industrial applications. A simple type of mortar consists of a cylindrical steel block with a hollow insert of hardened steel into which fits a pes­tle with a rounded end, the diamond dust being prevented from escaping along the sides by a rubber sealing ring. Automatic mechanical mortars are used in larger crushing opera­tions.

Diamond News and S.A. Jeweller, The. A monthly trade journal that

Diamond Manufacturers' and Im­porters' Association of America PDF Print E-mail
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Tuesday, 18 September 2007

diamond Manufacturers' and Im­porters' Association of America, Inc.

A trade association of firms and companies in America that import or cut and polish Diamonds or that deal in rough diamonds at the wholesale level. Some import rough diamonds, fashion them into finished gems and sell them for use in jewelry; others import or buy finished gems only. The work of the Association includes representing the employers in negotiating with the unions, prepar-

ing memoranda for use by the trade, cooperating with American and foreign governments in efforts to check diamond smuggling, repre­senting the industry before the Un­ited States Tariff Commission, and cooperating with the Federal Trade Commission to stop misleading ad­vertising and misrepresentation in the sale of diamonds. Headquarters of the organization is located at 342 Madison Avenue, New York City.

DiamondLite (trademark, Gemolog-ical Institute of America PDF Print E-mail
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Tuesday, 18 September 2007

DiamondLite (trademark, Gemolog-ical Institute of America). An in­strument for color grading Diamonds by visual comparison with master diamonds. It affords a constant source of artificial light that is the equivalent of north daylight and eliminates reflections from surround­ings; also, it restricts dispersion of the light passing through the stone. The instrument incorporates a longwave ultraviolet tube for detect­ing fluorescence in diamonds and other stones. Also called Diamolite. See color grade, fluorescence, cia color-grading system, master diamonds, north daylight

Diamondlux (trademark,^ Gemologi-cal Institute of America). A special overhead light fixture, introduced in 1959, for jewelry-store illumination. The unit consists of a combination of special fluorescent tubes, the effect of which is to produce a daylight-equivalent illumination to show ob­jects in their true colors. A unique pattern and type of baffles produces individual light sources, yielding a degree of dispersion and scintillation in gems not seen in other present types of illumination. These soft, pinpoint sources of light make possi­ble, for example, the demonstra­tion of the comparative beauty of diamonds cut to different propor­tions. The same lighting unit, but without the baffles, is known as the Verilux.

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