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lumpy Lunda lupren luster PDF Print E-mail
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lumpy (or thick) stone. A cut dia­mond that is unnecessarily deep, re­sulting in a loss of brilliancy. Stones are cut in this manner to gain addi­tional weight from the rough, thus permitting them to be sold at lower per carat prices. Lumpy stones were common before the advent of the diamond saw, for much more weight could be retained from crystals of oc­tahedral shape, if little were ground away from the crown and pavilion tips. See tolkowsky theoretical bril­liant cut, too deep pavilion cut. (See photo.)

Lunda. An important diamond-bearing region in Angola. See angola.

lupe. The German equivalent of loupe.

lupren. Scandinavian diamond No­menclature system (Scan. D.N.) term for internally flawless (IF).

luster. The appearance of a material's surface in reflected light, as deter­mined by the quantity and quality of light reflected. Smoothness and re-


fractive index are the main factors af­fecting luster. The luster of most rough Diamonds is described as greasy; that of fashioned Diamonds as adamantine (from the Greek word adamas, meaning extraordinarily hard).

Lusterite. Trade name for synthetic rutile.

Lustigem. Trade name for man-made strontium titanate.

Ludwig Luebo Luembe River lumps PDF Print E-mail
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Luachimo River. A river in Angola, Africa, the basin of which is an im­portant diamond-mining region. See


Lubilash. A district comprising the valley of the Lubilash River in the Republic of Zaire, formerly the Congo Republic. It is a major pro­ducer of Diamonds, and is mined by Socie'te Miniere du Beceka. For a number of years, the output from the several mines in the area has ex­ceeded 12 million carats annually, mostly (about 97%) of industrial quality. It is a highly mechanized, ef­ficient operation. This area is also known as Bakwanga, after the city and central treatment plant location maintained by Be'ceka. Mining is currently proceeding both in alluvial deposits and in kimberlite pipes. See


Luderitz. A town near the north end of Consolidated diamond Mines of South-West Africa, Ltd. It was once the center of the South-West African

diamond industry, and the adminis­trative headquarters first of the Ger­mans and later C.D.M. See south-west


Ludwig, A. An Austrian chemist who, in 1901, recorded the formation of what he thought were Diamonds when he passed an electric current through an iron spiral embedded in powdered gas carbon in an atmos­phere of hydrogen and under great pressure. In a later experiment he fused a mixture of carbon and iron in an electric stream and suddenly chilled the mass by admission to it of water under a pressure of 2200 at­mospheres. Under these conditions of instantaneous cooling, Ludwig claimed to have synthesized minute Diamonds. There is no proof that his experiments were successful. See

SYNTHETIC diamond.

Luebo. A major diamond-mining area in Kasai Province, Republic of Zaire. It lies between the Lulua and Luebo Rivers and is exploited by Beceka, Forminiere, and the E. K. L. Consortium. Production from this area, also known as the Kasai Dis­trict, is usually between 500,000 and 1,000,000 carats annually, of which 30% or more are Gemstones. See re­public OF ZAIRE.

Luembe River. A river in Angola, Af­rica, the basin of which is an impor­tant diamond-mining region. See an­gola.

luminescence (loo'-meh-nes"-cence). A general term used to de­scribe the emission of certain wavelengths of light by a diamond or other substance when excited by radiation of different wavelengths, electrical discharge, heat, friction or

a similar agency. See fluorescence, cathodoluminescence, phosphorescence, ultraviolet, premier diamond, photo-luminescence, emission spectrum.

lumps. Large pieces of kimberlite, or blue ground, that failed to disinte­grate in the time allotted on the weathering floor. These are later worked through recovery processes and reported separately. See kimber­lite, floor.

lumpy girdle. An unnecessarily thick girdle on a brilliant-cut diamond. See girdle, girdle thickness, knife-edged girdle, bearded (or fuzzy) girdle, polished girdle.

loupe louped lower-break facets lozenge facet PDF Print E-mail
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Friday, 21 September 2007

loupe (loop). Any small magnifying glass mounted for use in the hand as a hand loupe, or so that it can be held in the eye socket or attached to spectacles as an eye loupe. A loupe may contain a single lens (uncor­rected) or a system of lenses (cor­rected), which in commercial usage range from 2 to 20 power or more. The usual jeweler's or watchmaker's loupe is uncorrected and magnifies from 2 to 3 times; aplanatic loupes (those that are corrected for spherical aberration) vary from 6 to 20 power. In order to pronounce a diamond flawless by the American Gem Soci­ety definition or perfect by Federal Trade Commission Trade Practice Rules, the minimum specifications for a magnifier call for a 10x loupe corrected for spherical and chroma­tic aberration. See aberration.
"loupe clean." A term that is usuaily misleading, since it is used in de­scribing diamond qualities to suggest that no flaws are visible under mag­nification. If this were true under 10x examination by an experienced man using a corrected loupe, the term perfect or flawless would be used. It is prohibited by the American Gem Society for use by its members. It is also prohibited by the Federal Trade Commission, unless the stone is flaw­less.

louped. A trade term meaning that a diamond or other gemstone has been examined and probably graded by using a loupe.

low cape. See cape.

lower-break facets. See girdle facets

lower-girdle facets. See girdle facets

lozenge cut (loz"-enj). A four-sided form of cutting, usually step cut, re­sembling a playing-card diamond in outline.

lozenge facet. A term sometimes used synonymously with the four quoin facets (bezel or top-corner facets) on the crown of a brilliant-cut diamond. Some cutters use the term for the four pavilion-main facets or bottom-corner facets. See quoin facet, bezel facet, pavilion facet

Lottery Diamond Louis Cartier Diamo Louis XIV Diamondnd PDF Print E-mail
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Friday, 21 September 2007

Lottery diamond. See pigott diamond. Loughead, Victor. An American in­vestigator who, during the early part of the 20th century, attempted to produce synthetic Diamonds by a process involving a thermite reaction in a closed container under high pressure — a process similar to that used by Friedlander. See synthetic


Louis Cartier diamond. This flawless and colorless pear-shaped gem weighs 107.07 carats and is reported to be worth $5 million. The 400-carat rough was discovered in Sep­tember 1974 in South Africa and took almost two years for its cutting. Two other stones will be cut from the rough. They will be named the Louis

Cartier II and Louis Cartler III. It was named the Louis Cartier diamond in honor of the third-generation de­scendant of the French founder of the firm. The stone was made avail­able for public viewing on October 13, 1976, in New York City and was later exhibited in Paris and London.

Louis XIV diamond. This pear-shaped diamond prior to 1953 weighed 62.05 carats and reportedly belonged to Louis XIV of France. It is possible that this is one of the many Indian Diamonds brought to Europe by Tavernier. In 1958 Harry Winston purchased this diamond from the estate of the late Mary B. Foy, daugh­ter of Jack Chrysler, and recut it to a flawless 59.46-carat pear shape. It was exhibited in the Louvre in 1962 for the "Ten Centuries of French Jewelry Exhibition." In 1964, it was
Louis XIV diamond. 59.46 carats. Courtesy Harry Winston, Inc., New York City.

Lobaye Loffa River LIBERIA. PDF Print E-mail
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Friday, 21 September 2007

Lobaye. A minor diamond-mining area in the Central African Republic.

Loffa River. The site of the discovery of an alluvial diamond deposit in 1955 in Liberia, West Africa. See


L'office Forestiere et Miniere du Congo. (FORMINIERE). One of the

principal diamond-mining com­panies in the former Congo Repub­lic, now in the Republic of Zaire. Recent production has been approx­imately 400,000 carats annually. See


London. The name of a minor al­luvial diamond deposit in the Schweizer Reneke area, Transvaal Province, Republic of South Africa. The yearly production from this de­posit is insignificant.

long hexagon cut. A modification of the hexagon cut, the shape of which is produced by increasing the length

Long hexagon cut

of one of the three pairs of sides. It resembles a baguette with two pointed ends.

Longlands. A minor alluvial diamond deposit in the Barkly West area, Cape Province, Republic of South Af­rica. The total production in one re­cent year was 326 carats.

lonsdaleite. A hexagonal allotrope (polymorph) of diamond which has been found in meteorites and syn­thesized from graphite in the labora­tory by shock conversion. It is clas­sified as a Type III diamond.

loopkring. A Dutch word that refers to the inner section of the polishing lap, or scaife. It is on this part of the lap that the facets of a diamond are cut, or placed. Polishing and the removal of cutting marks is ac­complished on the outer section of the wheel, called the zoetkring. See


loose goods. Polished but un­mounted Diamonds. See goods.

lot. (1) A group of rough Diamonds offered for sale by the diamond Trad­ing Co. to firms invited to view its sights. A lot usually includes a wide variety of material. (See sights.) (2) Also applied by diamond merchants to their regroupings of these dia­monds according to color, make, and

comparative freedom from imperfec­tions after fashioning. (3) Lots can also be composed of polished stones.

Litkie Diamond NAMAQUALAND Little Sancy Diamond PDF Print E-mail
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Friday, 21 September 2007

Litkie diamond. Found on the Vaal River, Cape Province, Republic of South Africa, 1891. 205 carats. Loca­tion unknown.

Little (or Lesser) Namaqualand. See


Little Sancy diamond. Although from the collection of the same Seig­neur de Sancy of the French Court, this 34-carat pear-shaped brilliant cut should not be confused with the 55-carat Sancy diamond. The Little Sancy was bought by Prince Fre­derick of Orange in 1647 and passed down to his grandson, who became King Frederick I of Prussia. The gem was then in the Prussian Treasury for many years. It was worn on the Crown Necklace by the bride, Prin-

cess Mary of Sachen-Altenburg, at her wedding to Prince Albert of Prus­sia in Berlin in 1881. In 1923, it was inventoried among the Crown Jewels of the Hohenzollern as a pendant in a 23-diamond necklace. Today, still mounted as a pendant but of a much simpler design, the Little Sancy is one of the prize possessions of the Royal Prussian House in Bremen, Germany. An alternate name is the Beau Sancy.

load. A term used in the South Afri­can diamond mines for 16 cubic feet of blue ground, or about 4/5 of a short ton. Despite the fact that mine cars carry about 20 cubic feet, the standard load used for reporting yield is the 16-cubic-foot size.

light off-color light yellow COLOR-GRADING SYSTEM Dictionary PDF Print E-mail
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Friday, 21 September 2007

light off-color. A color-grading term used at the mines for a color better than off-color but inferior to second bye.

light yellow. A trade term used by some dealers to cover a wide range of colors in the low end of the dia­mond color-grading scale. Stones in this broad classification show a very obvious yellow tint to the unaided eye. For an approximate comparison of this grade to those used in the color-grading system of the Gem­ological Institute of America and the American Gem Society, refer to chart in Appendix entitled, Com­parison of Different diamond Color-Grading Systems. See also cia


limonite. One of the alteration min­erals found in the kimberlite of the South African diamond mines. A yellowish-brown hydrous oxide of iron.

limpid (or limpidity). A diamond is said to be limpid if it is without body color and very transparent.

Linde Simulated Diamonds. Trade name for man-made yttrium alumi­num garnet (YAG)

1. Linobate. Trade name for man-made lithium niobate. See lithium niobate. Lisa Blue diamond. Originally de­scribed as a soft sky-blue-colored brilliant weighing 37.21 carats. At one time it was believed set in one of the crowns of the Emperor Char­lemagne. It was later recut to 37.05


carats and reported to be flawless and of a rare fancy blue color. This diamond set in a clip was sold in 1961 by Harry Winston in Canada. In 1967 he repurchased the diamond and subsequently resold it in Europe. Lisbon cut. A rarely used modifica­tion of the old-mine cut with an ad­ditional 16 facets.

Lisbon cut

lithium niobate. Relatively rare col­orless to colored man-made dia­mond simulant. Its hardness is about 6, S.G. = 4.64, R.I. = 2.21-2.30, and has a high dispersion of 0.120 for the Fraunhofer B-G lines. Manufactured by the Czochralski pulling method

Liberia Lichtenburg light brown light-field illumination PDF Print E-mail
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Friday, 21 September 2007

Liberia. A diamond-mining country on the southwest (Guinea) coast of Africa. The first discovery was made in 1910 in alluvial sands along the Joblong and Boa Rivers, about 30 miles inland from the capital, Mon­rovia. In 1955, new alluvial finds were made along the Loffa River, Suehn-Bopolu district, Western Prov­ince, opposite Sierra Leone. The dis­covery precipitated such a rush and such chaotic conditions that the gov­ernment was forced to close the area to prospecting and mining until mid-1958, when certain restrictions were imposed. The approximately 50-square-mile area does not appear to be exceedingly rich. The majority of the stones exported from Liberia, until very recently, were apparently those smuggled into that country from Sierra Leone and possibly Guinea. diamond production ex-

ported in 1 975 reported to be approx­imately 165,000 carats industrial and 241,000 carats gem quality.

Lichtenburg. A town in the Transvaal Province, Republic of South Africa, in which many alluvial diamond diggings are located. It was a major producing field from the time of its discovery in 1925 until 1929, but production has since declined sharp­ly. The production was below aver­age in quality, consisting primarily of cleavages and industrials. The large output from this field, plus the onset of the Depression, posed such a threat to price stability that the diamond Corporation, Ltd., was founded to buy stones in order to hold them off the market, thus stabilizing prices.

light brown. See brown diamond.

light cape. See cape.

light-field illumination. A type of il­lumination in which the light source is directly behind the diamond or other gemstone being observed. This principle, together with dark-field il­lumination, is incorporated in the Cemolite, or Cemscope (trademark, Gemological Institute of America) and the Diamondscope (trademark, American Gem Society).

Light of Faith diamond. See nur-ud

DEEN diamond.

Light of India diamond. One of two

large Diamonds (the other being the Rajah diamond) that belonged to the late Boston socialite, Mrs. Jack Gardner, which she had bought from Tiffany's in 1886. Listed in the bill of sale were two weights, 12.38 carats and 25.5 carats, but it did not specify to which diamond they belonged. Worn as a hair ornament, set on a spring, to wave about the head like


an antenna. Owned by another Bos-tonian; name undisclosed. See rajah


Leveridge gauge Levinson Prospection Liberator Diamond PDF Print E-mail
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Friday, 21 September 2007

Leveridge gauge. A millimeter dial micrometer, designed by A. D. Leveridge, for measuring both mounted and unmounted Diamonds and colored stones of various styles of cutting. An accompanying set of tables is used for translating mea­surements into weights. It is the most accurate of the gauges designed specifically for weight estimations.


Levinson Prospection. A small dia­mond-mining concern that works diamondiferous terraces south of the Kunene River, which forms the fron­tier with Angola, in the extreme north of South-West Africa.

Liberator diamond. In honor of Simon Bolivar, nineteenth-century liberator of Venezuela, who was af­fectionately called El Libertador by his countrymen, this top-quality 155-carat diamond was given the name Liberator. It was discovered by three miners in 1942 in the Gran Sabana diamond-bearing region of Venezuela. Purchased in 1943 by Harry Winston, New York City gem dealer, it was cleaved into two pieces weighing 115 and 40 carats. These cleavages, in turn, were fashioned into four stones: three emerald cuts of 39.80, 18.12 and 8.93 carats, and a 1.44-carat marquise. Fifty-six per­cent of the original weight was lost in the cutting process. Winston used the three smaller stones in an elabo­rate clip and sold the 39.80-carat stone to Mrs. May Bonfils Stanton, Denver, Colorado, heiress and phil­anthropist, in 1947. In 1962, he ac­quired the stone a second time, purchasing it from the New York auc­tion galleries of Parke-Bernet, Inc., from the jewelry estate of Mrs. Stan­ton for $185,000. The Liberator is set in a platinum ring with two tapering diamond baguettes.

Lesotho B Diamond CULLINAN (II) DIAMOND Letny Diamond PDF Print E-mail
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Friday, 21 September 2007

Lesotho B diamond. This large rough weighing 527 carats was one of the three largest Diamonds ever found in Lesotho. It was discovered in 1965 and bought by Mr. E. J. Sera-fini of Bloemfontein and Maseru for $162,400. The Lesotho B was later resold to an unknown American dealer in Antwerp. Present disposi­tion is not known.

Lesotho C diamond. Discovered at the Kau diggings, Lesotho, in 1969, this large brown rough weighing 338 carats was initially sold for $54,740. It was reportedly cut into 10 stones in Amsterdam of which the largest gem

is a 24-carat marquise. The where­abouts of these Diamonds is un­known today.zesser

Star of Africa diamond. See

CULLINAN (II) diamond.

Lestergem. Trade name for synthetic spinel.

Letny diamond. A 46.36-carat rough found in Mirnyy, Yakutiya, Siberia, sometime after 1955. Now in the Russian diamond Fund at the Krem­lin.

Letseng-la-Terai pipe. diamond bearing kimberlite pipe in the Drakensberg Mountains of north­eastern Lesotho. Highest diamond diggings in the world at over 10,200 feet where snow covers the area for about three months a year and tem­peratures plunge to sub-zero. Some-

times spelled Letseng-la-Draai. The surface area of the pipe is about 20 hectares and is covered with a thin layer of black soil. Smaller satellite pipes surround the deposit. Several large Diamonds have been reported found at Letseng-la-Terai, significant among these are the pale brown col­ored 601.25-carat Lesotho diamond discovered in 1967, a 147-carat stone

in 1969, and a 155-carat off-white octahedron found in 1973.

Le Grand Sancy Diamond Le Grand Sancy Diamond Lesotho Lesotho Diamond PDF Print E-mail
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Friday, 21 September 2007

Le Grand Sancy diamond. See sancy


Leicester Mine. A small diamond pipe mine in the Barkly West area, Cape Province, Republic of South Af­rica. It is owned by Carrig Dia­monds, Ltd.

Leopold diamond. A 10-carat bril­liant. Given by King Leopold III of Belgium to his late wife, Queen As-trid, mother of present King Bau-douin. Exhibited at Newark, New Jersey, Museum, 1948. Owned by an undisclosed private collector.

Lesotho. Prior to 1966, it was known as the High Commission Territory of Basutoland. Totally surrounded by the Republic of South Africa, Lesotho consists of a central high plateau with lowlands to the west and high­lands to the east with elevations up to 11,000 feet in the Drakensberg Mountains. Diamonds occur in the northern part of the country at the Letseng-la-Terai mine, and other pipes. De Beers is in the process of preparing this pipe for extensive min-

diamond areas of Lesotho

ing, despite a very low diamond production in terms of carats per load. The rationale is that there may be enough large stones to make the gamble worthwhile. diamond pro­duction in 1975 was reported to be 2,000 carats industrial and 1,000 carats gem quality.

Lesotho diamond. The Lesotho diamond was discovered in Lesotho, Africa, in May, 1967 by Mrs. Ernes­tine Ramoboa at the Letseng-le-Draai diggings. The brownish-colored rough weighed 601.25 carats and was sold for $302,400 at auction in Maseru, the capital of Lesotho, to a South African dealer. He, in turn, sold it to a European dealer. This diamond was later purchased in Ge­neva by Harry S. Winston of New York, who subsequently cut it into 18 stones totaling 242.50 carats, in 1969. Most diamond cutting styles


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