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Jubilee Diamond Institution 48.42-carat briolette-cut diamond PDF Print E-mail
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Friday, 21 September 2007

Jubilee diamond. A 245.35-carat, cushion-shaped, brilliant-cut dia­mond of unsurpassed color, clar­ity, brilliance and symmetry — a diamond so perfectly proportioned that it can be balanced on its culet, which is less than two millimeters in diameter! Such is the description of the world-renowned jubilee Dia­mond. South africa's famous Jagers-fontein Mine produced this cele­brated diamond crystal in 1895. It had an irregular shape, somewhat like a flattened octahedron, but without definite crystal faces. It was first known as the Reitz Diamond, in honor of President F. W. Reitz of the Orange Free State. The cutting of the stone took place in 1897 (the year of Queen Victoria's Diamond Jubilee, from which the stone derived its name). A 13.35-carat pear shape also was cut from the same crystal, but its ultimate disposition is unknown. The jubilee was exhibited at the Paris Ex­position of 1900, where it received world-wide attention and the high praise of gem experts. Shortly there­after, it was sold to Sir Dorab Tata, a Parsi of Bombay and the founder of the Indian iron-and-steel industry, who owned it until his death. (Note: A Pars/ is a person of Persian des­cent, usually an affluent and highly educated citizen of Bombay City and State, who is an adherent of the an­cient Persian religion called Zoroas-trianism.) In 1939, the executors of Tata's estate sold the stone through Cartier, Ltd., London, to Paul-Louis Weiller, a wealthy and well-known patron of the arts. Weiller lent the jubilee in 1960 to the Smithsonian

Institution, Washington, D.C., for an exhibit. In 1966, it was shown at the De Beers Diamond Pavilion in Jo­hannesburg. Rough weighed 650.80 cts.

Julius Pam Diamond. A 246-carat diamond found in the Jagersfontein Mine, Republic of South Africa, in 1889. It weighed 123 carats after cut­ting. The present location is un­known. It should not be confused with the Pam Diamond. June Briolette Diamond. The June Briolette is a pale, greenish-yellow


48.42-carat briolette-cut diamond. It is suspended in a pin formed of a wreath of oval, round and pear-shaped Diamonds of matching col­ors. Created and owned by Julius Cohen, New York City manufactur­ing jeweler, the jewel is valued by him at $140,000.

Juscelino Kubitschek Diamond. A

174-carat diamond that was found in the Municipality of Estrela do Sul, Minas Gerais, Brazil, in 1954. Addi­tional details are not known.


Last Updated ( Friday, 21 September 2007 )
 
Joblong River Jonker Diamond purchased by private gem collector PDF Print E-mail
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Friday, 21 September 2007

Joblong River. A river in Liberia, the gravels of which are a very minor source of alluvial Diamonds. See

LIBERIA.

Johannes Gem. A trade name for synthetic rutile.

Jonaskop. A minor alluvial diamond deposit in the Barkly West area, Cape Province, Republic of South Af­rica. The annual production for this digging is insignificant.

Jonker Diamond. In January, 1934, a 726-carat diamond was found on the property of Jacobus Jonker in an alluvial deposit on his farm at Elandsfontein near Pretoria, Republic of South africa. The stone was of unusually fine color and purity. It was purchased by the Diamond Pro­ducers' Association for $315,000 and was later sold to Harry Winston, New York City gem dealer, for a re­ported $700,000. The diamond was entrusted to Lazare Kaplan, master cutter, who produced a marquise and 11 emerald cuts from it. The Ma­harajah of Kapurthala bought two of the smaller diamonds for mount­ing in a ring; the other nine were


purchased by private gem collectors. The largest stone, called the jonker Diamond, was a 66-facet emerald cut that weighed 142.90 carats; it was recut in 1937 to 125.65 carats and 58 facets, to give it a more ob­long outline. The Jonker was sold to Farouk while he was still King of Egypt. After he went into exile in 1952, the location of the stone be­came a mystery. In 1959, however, there were rumors that Queen Ratna of Nepal was wearing it, and it has since been confirmed that the late Farouk did sell the great diamond to the little country in the Himalayas for a reputed $100,000. The jonker Diamond No. 4 was sold in October, 1975, to an unidentified South American at the Sotheby Parke-Bernet auction in New York City for $570,000. Reportedly, the jonker was sold in Hong Kong to an un­known businessman for $4,000,000 in 1974.


Journado diamond. A misnomer for a colorless imitation stone.

journaleiro. A Brazilian term used by native prospectors and miners to refer to a location where they feel sure of finding diamonds.

jubilee cut. A rarely used modifica­tion of the brilliant cut, in which the table and culet are replaced by ex­tended star facets and other modifi-


Jubilee cut

cations are made in other facets, making a total of 88 facets. It was named in commemoration of the 60th anniversary of Queen Victoria's accession in 1897.

 
jig jigger Joao Neto de Campos PDF Print E-mail
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Friday, 21 September 2007

jig. A mechanical sieve used to sepa­rate Diamonds and other heavy mate­rials from lighter, worthless material. It is constructed of two compart­ments and filled with water. In one compartment a plunger works up and down. In the other compartment is a screen mounted several inches below the level of the water. The screen is covered with heavy gravel of a size too large to pass through the meshes. As the plunger moves up and down it produces a like move-


ment in the water in the pulsator. The water, as it moves up in the screen compartment, lifts the gravel and the concentrate that has been fed in with it and then drops it. Thus the heavy material is able to work its way through the large gravel and fall through the screen into the bottom of the box. The lighter material is un­able to penetrate the mass of gravel, and is pushed along by the incoming water and concentrate until it is forced over the edge of the jig and taken to the tailings heap. The mate­rial that falls to the bottom includes the diamonds and other heavy min­erals. Also called pulsator jig. Note: jig largely replaced by heavy-media cone separators.

jigger. A workman who sorts or cleans ore by the process of jigging. See jig.

Joao Neto de Campos. Found on the Paranaiba River, Catalao district, Goyaz, Brazil, 1947. The weight of the rough is reported to be 201 carats. Further details lacking.

 
Jalmeida Diamond jargon Jewel Box Jewelers' Security Alliance of the United States PDF Print E-mail
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Friday, 21 September 2007

Jalmeida diamond. A light-yellow stone weighing 109.50 carats in the rough. Discovered in the Bandeira River, Goyaz, Brazil, in 1942. Origi­nally acquired by Steinbert & Byr-kett, Rio de Janeiro jewelers. Report­edly cut to 45.40 carats. No addi­tional information.

jargon. A term once used for an in­ferior diamond having a yellowish color. May be confused with jargoon, a variety name for colorless zircon.

Jarra Gem. Trade name for synthetic rutile.

Java Gem. A trade name for synthet­ic rutile.

Jeffries, David. Prominent English jeweler and diamond expert of the 18th century. Author of "A Treatise on Diamonds and Pearls," published in 1750, in which he set forth rules for the evaluation of rough and fashioned diamonds and discussed their subsequent manufacture.

Jewel Box. A popular name given to a section of kimberlite in the old Roberts-Victor Mine, Republic of South africa, that was a particularly prolific producer of fine-quality dia­monds.

Jewelers' Security Alliance of the United States. A mutual, non-profit association, organized in 1883 for the protection of the jewelry industry. The Alliance offers many services and cooperates with all law en­forcement agencies; investigates crimes, prevents the commission of crimes by advocating burglar alarms and protective devices; supplies free detective services, provides members with warning signs; issues informa­tion on how to prevent various kinds of jewelry-related crimes. Headquar-


ters: 6 East 45th Street, New York,

New York 10017.

Jewelers' Vigilance Committee. A

non-profit association founded in 1912 to advance ethical practices in the jewelry trade. It is composed of representatives of every branch of the jewelry industry. The Commit­tee's purposes are: to be prepared to meet promptly any situation which imperils any broad interest in the trade; to protect the trade's prestige and endeavor to maintain public confidence in the jewelry industry, particularly the retailers; to fight any discrimination against the trade through government action; to help maintain fair competition within the industry; to develop and help main­tain trade standards on the highest possible levels; to assist in the pros­ecution of violators of the various laws, rulings, and regulations per­taining to advertising; to correct nomenclature and quality markings; to assist the government to combat smuggling and protect the industry from it; and to keep the trade in­formed of laws and regulations af­fecting its business. Headquarters: 919 Third Avenue, New York, New York 10022.

Jewelite. Trade name for man-made strontium titanate.

Jewelry Industry Council. This is the nationwide publicity and promo­tional organization of the entire in­dustry, with a membership consisting of jewelry retailers and suppliers. Its basic objective is to keep retail jewelry sales at the highest possible level. This is accomplished by the following activities: it prepares and releases for newspapers, magazines,


radio and television and other com­munications media a steady stream of publicity stories about the desira­bility of jewelry-store merchandise. It creates and furnishes sales-pro­motional material for retailers, in­cluding booklets for public distribu­tion, advertising and display ideas for newspapers, direct-mail service, radio commercials, window displays, Christmas portfolios, display cards for gift occasions, speech manu­scripts and fashion reports. Head­quarters: 608 Fifth Ave., New York City 10020.

 
Jagersfontein Rough Diamond Jahangir Diamond PDF Print E-mail
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Friday, 21 September 2007

Jagersfontein Rough diamond. A 215-carat diamond that was found in the Jagersfontein Mine, Republic of South africa, in 1881. There seems to be no record of its being cut. The ul­timate disposition of this stone is not known.

Jahangir Diamond. The inscriptions on this 83-carat diamond indicate that it was an heirloom of the em­perors of the Mogul Dynasty and was probably used to hold the ceremo­nial plumes on their turbans in place. The Persian engravings show that it first belonged to the Emperor Jahan­gir and then to his son, Jehan. In 1954, it was sold in London by its owner, the Maharajah of Burd-wan, to Stavros S. Niarchos, Greek shipbuilder and industrialist, for £13,000. In 1957, the Jahangir again changed ownership, this time being sold to an Indian businessman, C. Patel, for £14,000, in whose posses­sion it presumably rests today.

 
jaca Jacob Diamond Jager (yah"-ger) Jagersfontein Brilliant Diamond PDF Print E-mail
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Friday, 21 September 2007

jaca. A Brazilian term for spots in Diamonds.

Jacob diamond. Long identified with the Nizam of Hyderabad, the 100-carat Jacob was reported to be for sale in 1951, together with a large part of the Nizam's jewels. In 1956, it was held for sale by the Bank of India for $280,000. An American dealer at that time described it as "white, not blue" and not the most brilliant gem he had seen. The pres­ent owner of this diamond is not known.

Jacobs, Erasmus. A 15-year old farmer's boy who is credited with the discovery of the first diamond in South africa, in 1866. The stone that he found near the Orange River weighed 21.25 carats. See oreilly

DIAMOND.

Jager (yah"-ger). A term used to des­ignate a stone that displays a faint tint of blue. The name was adopted from the Jagersfontein Mine, since a relatively high percentage of its pro­duction consists of such stones. The blue tint associated with these stones is usually, but not always, the result of strong blue fluorescence. See fluorescence, blue diamond, jagersfontein

MINE.

Jagersfontein Brilliant Diamond. See

PAM DIAMOND.

Jagersfontein Mine (yah'-gers-fon-tane"). The first diamond pipe mine in South Africa, discovered in 1870 on the Jagersfontein farm near Fauresmith, Orange Free State. The


Jagersfontein Mine was closed May 28, 1971. Although the mine pro­duced a large proportion of cleavage fragments and heavily spotted goods, the output was characterized by a high proportion of fine colors, in­cluding stones that appear faintly blue in daylight; such stones usually, but not always, owe their color to strong fluorescence. The Excelsior, the Jubilee, and other large but un­named diamonds were found there. Annual production was usually be­tween 100,000 and 150,000 carats. See iager, fluorescence. Jagersfontein R
 
Isabella Diamond Isle of Wight diamond. Israel Export & Trust Corporation Ituiutaba Diamond PDF Print E-mail
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Friday, 21 September 2007

Isabella diamond. A 65/8-carat diamond reportedly owned by Queen Isabella of Spain. It was the pendant in a necklace given to Baby Doe Tabor of Colorado by her sec­ond husband, Senator Tabor, the "Bonanza King," in 1883. After Tabor lost his fortune, Baby Doe sold her jewels and the whereabouts of the Isabella is unknown today.

Isle of Wight diamond. A misnomer for rock crystal.

isometric system. See cubic system.

isotropic (ice'-oh-trope"-ik). See

SINGLE REFRACTION.

Israel. See cutting centers.


Israel Export & Trust Corporation.

An organization in the Ivory Coast that owns a license authorizing it to import and export Diamonds. See

IVORY COAST.

Ituiutaba Diamond. Found in 1940 in the Ituiutaba Mine, Minas Gerais, Brazil. 105 carats. Disposition un­known.

Ivory Coast (Cote d'lvoire). An au­tonomous republic that was formerly a French colony a part of French West africa. It is an important pro­ducer of alluvial diamonds. The min­ing companies operating in the Ivory Coast are Societe de Recherches et d''Exploitations Minieres en Cote d'lvoire (SAEAMCI) and Societe Diamandtifere de la Cote d'lvoire (SAREMCI). Diamond production in 1975 was reported to be 125,000 carats industrial and 84,000 carats gem quality. See French west africa.


 
Iranians iris diamond irradiated diamond PDF Print E-mail
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Friday, 21 September 2007

Iranians. A study of the Crown Jewels of Iran in 1966 by Dr. V. B. Meen and Dr. A. D. Tushingham revealed that there were 23 large Diamonds which they named the Ira­nians. There are 19 yellow stones of South African origin which were probably acquired in 1889 by Shah Nasir ud-Din during his trip to Europe. Four diamonds that may be of Indian origin include Iranian 19, 22, and 23, which are white stones, and Iranian 20, a peach-colored diamond. Iranian 23, weighing 38.18 carats, is thought by some experts to be the Hornby which was described by Edwin Streeter in 1882. The Ira­nian listed weights (ct.), shapes, and colors are:

1 152.16 rectangular old bril-

liant; silver cape

2 135.45 high (old) cushion, bril-

liant; cape

3 123.93 high (old) cushion, bril-

liant; silver cape

4 121.90 multifaceted octahed-

ron; cape

5 114.28 high (old) cushion bril-

liant; silver cape

6 86.61 rounded triangular bril-

liant; cape

7 86.28 irregular Mogul cut;

silver cape

8 78.96 high (old) cushion bril-

liant; cape


9 75.29 high (old) cushion bril­liant; cape

10 75.00 pendeloque brilliant;

silver cape

11 75.00 pendeloque brilliant;

silver cape

12 72.84 irregular pear-shape;

champagne

13 65.65 rectangular (old) bril-

liant; cape

14 60.00 cushion brilliant; yellow

15 57.85 round brilliant; silver

cape

16 57.15 cushion brilliant; silver

cape

17 56.19 cushion brilliant; silver

cape

18 55.67 cushion brilliant; cape

19 54.58 irregular oval Mogul

cut; colorless

20 54.35 high (old) cushion bril-

liant; peach

21 53.50 high (old) cushion bril-

liant; silver cape

22 51.90 elliptical Mogul cut;

colorless

23 38.18 multifaceted trapezoid

cut; colorless

iris diamond. A European term for a diamond that has been given a coat­ing to cause iridescence, giving the appearance of increased dispersion. Irish diamond. A misnomer for rock crystal from Ireland.

irradiated diamond. A diamond that has been subjected to bombardment by fast electrons, neutrons, deute-rons, etc. The purpose of irradiation is to make the color of the stone more attractive and desirable. See cyclotron-treated diamond, electron-bombarded DIAMOND, PILE-TREATED DIAMOND.

irregulars and shapes. A grading term used at the mines for diamond



 
internal characteristic internally flawless Iranian Royal Treasury PDF Print E-mail
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Friday, 21 September 2007

internal characteristic-A general term used to refer to any internal im­perfections or flaw. See flaw, imperfec­tion.

internally flawless. A clarity grade which describes a diamond without internal imperfections or flaws but with minor surface blemishes such as scratches, small naturals, etc., which under a strict interpretation of the F.T.C. rulings would preclude its being called flawless. Usually, but not always, such stones can be im­proved to a flawless grade through polishing and with a negligible loss of weight.

internal strain. A stress set up in a diamond or other gemstone as a re­sult of structural irregularities or dis­tortion, usually brought about by an inclusion in the stone. See anomalous double refraction, polariscope.

intrusive rock. See igneous rock. Iran. See Iranian royal treasury

Iranian Royal Treasury. The Royal Treasury of Iran contains a number of famous Diamonds and an untold number of large stones with no re­corded history. It is unique in that the


currency of the country is backed not by gold reserves but by a huge col­lection of diamonds, pearls and other Gemstones. Among the famous dia­monds that are known to be in the Treasury are the Nur-ul-Ain, the Darya-i-nur, and the Taj-e-mah. One diamond weighing 38.18 carats is be­lieved to be the Hornby.

 
Industrial Diamonds of South-West Industrial Distributors inferior cleavage PDF Print E-mail
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Friday, 21 September 2007

Industrial Diamonds of South-West africa (1945), Ltd. (Indosa). The company that works Saddle Hill and Saddle Hill North in the Luderitz dis­trict of South-West Africa. See

LUDERITZ.

Industrial Distributors (1946), Ltd.

The organization within the De Beers-diamond Corporation struc­ture that purchases industrial dia­monds for classification and mar­keting through Industrial Distributors (Sales), Ltd.

Industrial Distributors (Sales), Ltd. The organization that classifies and markets to the industrial-diamond trade the industrial diamonds it purchases from Industrial Dis­tributors (1946), Ltd. This company now confines itself to the marketing of crushing bort and drilling dia­monds. All other diamonds are mar­keted through the Diamond Trading Co.

inert. No detectable reaction, such as fluorescence, to stimulus when exposed to radiation from X-rays, ul­traviolet or cathode rays. See fluor­escence.

inferior cleavage. A grading term used at the mines for a diamond block, or cleavage, that is more or less spotted and of poor color.

inherent vice. If an insured diamond is said to have suffered damage, the insurance adjustor must determine whether damage has occurred and, if


so, whether it is attributable to some characteristic weakness in the stone. Such weakness is called inherent vice. If damage has occurred, it is fully recoverable from the insurance company only if inherent vice is not involved.

in situ. A mineral found in place in a primary rock (i.e., diamond in kim-berlite), rather than in a position to which it has been transported by such agencies as water, wind, glacial action or gravity, is said to have been found in situ.

 
Indosa indrajudha Industrial Diamond Association of America, Inc PDF Print E-mail
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Friday, 21 September 2007

Indosa. See industrial Diamonds of

SOUTH-WEST africa (1945), LTD.

indrajudha. A Sanskrit word for dia­mond, meaning "Indra's weapon." industrial diamond. As a general term, it refers to nongem-quality diamonds that are suitable only for industrial tools, abrasives, drills, etc. Gem-quality crystals, however, are also used for tools and particularly for dies, where lack of both internal strain and flaws is required. In this capacity, such a stone would also be called an industrial diamond. See

BALLAS, BORT, CARBONADO, HEAT CONDUCTION, TYPE II DIAMOND.

Industrial Diamond Association of America, Inc. An organization com­posed of diamond-tool manufactur­ers and others associated with the American industrial-diamond indus­try. It aids its member firms by en-

 
Indonesia Indore Pears PDF Print E-mail
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Friday, 21 September 2007

Indonesia, Republic of. A minor, sporadic producer of Diamonds. Sys­tematic alluvial mining was being conducted by the natives when the Dutch first arrived in the 17th cen­tury. At that time, the producing areas were situated in the vicinity of Pontianak, on the west coast of the island of Borneo, along the Kupuas, Sikajan, and Landak Rivers. The most important deposits at the present time are in the vicinity of Bandjer-masin and Martapura, on the south coast. Most of the diamonds recov­ered are small, but a significant proportion are of gem quality. An ex­ceptional number of colored diamonds have been found. diamond production in 1 975 was reported to be 3,000 carats industrial and 12,000 carats gem quality. Occasional re­ports of new finds suggest that the Kalimantan (Borneo) deposits, all of which are alluvial, are not exhausted.

See TRI-SAKTI DIAMOND, KALIMANTAN.

Indore Pears. These are two pear-shaped diamonds weighing approx­imately 50 carats each. Originally from Indore, north-central India, they were once the property of Nancy Anne Miller of Seattle, who, in the 1920's, became the Maharanee of Indore, with much attendant public­ity. After her subsequent divorce from the Maharajah, she continued to live in Indore but the diamonds were sold to Harry Winston, New York City gem dealer, and exhibited by him at the Court of Jewels at the New York World's Fair in 1939. They are believed to have been sold by Mr. Winston in the mid-1950's. The Indore Pears were repurchased by Harry Winston, New York, in 1976 and sold later in the same year


through the Geneva branch of Harry

Winston, Inc.

 
imperfection impregnated diamond dressing tool included crystal Independencia Diamond PDF Print E-mail
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Friday, 21 September 2007

imperfect. The diamond imperfec­tion grade at the low end of the flawless-to-imperfect (or perfect-to-imperfect) scale. An imperfect diamond contains imperfections that are visible face up to the unaided eye or that have a serious effect on the stone's durability. See clarity grade.

imperfection. A general term used to refer to any internal or external flaw or blemish on a fashioned diamond; e.g. a feather, carbon spot, fissure, knot, scratch, natural, etc. The terms flaw, characteristic and imperfection are usually used interchangeably. See

BLEMISH, FLAW, INTERNAL AND EXTERNAL CHARACTERISTIC.


imperfection grade. See clarity grade. Imperial Diamond. See victoria

DIAMOND.

impregnated diamond dressing tool.

A multiple-diamond dressing tool that contains several Diamonds not in a pattern throughout the matrix of the tool.

included crystal. A crystal of diamond or other mineral enclosed during the growth process of the main diamond crystal. It may be transparent in nature or dark appear­ing and usually assumes an angular outline. Sometimes called a "bubble" by jewelers due to its appearance.

inclusion. Any visible internal foreign object, or any crystal or grain of the same material as the host, or any break in a diamond or other gemstone can be called an inclusion. Breaks such as fractures and cleav­ages, however, are not always con­sidered inclusions. Independencia Diamond. Found in 1941 on the Tyuco River, Minas Gerais, Brazil, 106.82 carats. Present location not known.


index of refraction. See refractive in­dex.

 
illusion setting imitation immersion cell PDF Print E-mail
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Friday, 21 September 2007

illusion setting. Setting in which a stone, usually a small diamond, is set in a large polished or reflective plate fixed by claws in order to increase its apparent size. This setting appears as a continuation of the stone and was developed by the French jeweler Massin in the late 19th century for small stones.

imitation. In its broadest sense, any­thing that simulates a genuine, nat­ural gem. Gemologically, the term is applied only to glass, plastics and other amorphous materials, as distin­guished from synthetics and assem­bled stones.

immersion cell. Any cell used to immerse a diamond or other gem-stone in a liquid as a means of over­coming reflection and refraction from its surface, thus providing more ef­ficient observation of its interior. Immersion cells usually have glass bottoms, to facilitate their use with microscopes, polariscopes, etc.

the refractive index of a stone. Also, a rough guide to the refractive index by the immersion contrast method of using known stones and comparing with an unknown one. The more useful liquids are listed with refrac­tive indices: water (1.33), clove oil (1.54), bromoform (1.59), monobro-monaphthalene (1.66), and methy­lene iodide (1.74).

Last Updated ( Friday, 21 September 2007 )
 
Idol's Eye Diamond dealer illicit diamond buyer PDF Print E-mail
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Friday, 21 September 2007

Idol's Eye diamond. Among the striking and costly jewels of the late Mrs. May Bonfils Stanton of Den­ver, Colorado, was a 70.20-carat diamond of fine purity and color known as the Idol's Eye. Its history starts in the early part of the seven­teenth century, when it was found in India's famed Golconda Mines. In 1607, the East India Co. seized the stone from its owner, Persian Prince Rahab, in payment for his debts. It disappeared for 300 years and was rediscovered in 1906 in the posses­sion of Sultan Abdul Hamid II of Tur­key as the eye of a sacred idol in the Temple of Benghazi. After being sto­len by the Sultan's messenger who sold it to a Paris pawnshop, it was purchased by a Spanish grandee and remained in a safe-deposit vault in London for several years. Later, it was owned by a European diamond


dealer. The Idol's Eye was acquired by Harry Winston, New York City gem dealer, who sold it to Mrs. Stan­ton in 1947 for $675,000. In 1962, it was sold at auction by New York's Parke-Bernet Galleries, Inc. to Harry Levinson, Chicago jeweler, for $375,000. Mr. Levinson exhibited the Idol's Eye at the 1967 Diamond Pavilion in Johannesburg. In 1973 Sotheby Parke-Bernet Galleries of New York presented it at auction, but the owner, Mr. Levinson, withdrew the diamond after a disappointing bid of $950,000.

igneous rock (ig"-ne-us). A major class of rocks formed by cooling and consolidation from the molten state. They are classified by their grain size and chemical composition. Those that crystallized at depth are known as intrusive, or plutonic; those that hardened at or near the surface are called extrusive. Those rich in silica are sometimes called silicic igneous rocks, and those poor in silica are known as mafic igneous rocks. Kim-berlite, the source of Diamonds, is a mafic igneous rock. See kimberlite,

MAFIC, SILICIC.

illicit diamond buyer. One who buys rough diamonds from those who have obtained the stones through il­legal channels. The biggest volume of such buying is from unlicensed miners working surreptitiously on concessions granted to other com­panies.

Illicit Diamond-Buying Act. A South African law, passed in 1885, that makes the buying of diamonds from native laborers and others not enti­tled to their possession a criminal of­fense.

 
Ice Queen Diamond. See Idar-Oberstein BRILLIANT CUT Identigem PDF Print E-mail
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Friday, 21 September 2007

I. The abbreviation for imperfect. Icabaru. One of the principal alluvial diamond deposits in the Gran Sabana field, Venezuela. See Ven­ezuela.

Ice Queen Diamond. See niarchos

DIAMOND.

Idar-Oberstein. Although perhaps better known as the center of colored stone cutting, this West German town is now the hub of a major diamond-cutting industry (including Brucken, Hanau and Odenwald) that employs several thousand workers.

See CUTTING CENTERS.

ideal brilliant. Same as "ideal cut."

"ideal cut." See tolkowsky theoretical

BRILLIANT CUT.

identifying characteristics. A term employed by some diamond men in place of imperfections or flaws to de­scribe blemishes and inclusions in Diamonds and other stones.

Identigem. A diamond grading "fingerprint" system introduced by the Diamond Grading Laboratories Ltd. of Hatton Garden in the early 1970's. Cut and clarity grades are based essentially on the Scan D.N. system. Eight separate tests, compris­ing the portfolio of any given diamond, are permanently recorded as a "fingerprint" in a Central Com­puter Clearing House, as well as on microfilm. The eight tests include: Weight, Cut, Clarity, Color, Color Print, Crystal Print, Goniometer Con­tour Print, and Grades of Polishing. See color print, crystal print.

 
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