Diamond Dictionary

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.

Hyderabad. A state in India; also the name of its capital city. The modern name for Golconda, the ancient source of some of the world's finest and most famous Diamonds. The old fortress of Golconda is situated seven miles northwest of the present city.

See GOLCONDA, INDIA.

hydro-cyclone separation. A gravel concentrating process which uses the hydro-cyclone, a very efficient ma­chine employing the same princi­ple as the heavy media separator. Gravel and broken blue ground are fed in from the side and a centrifuge motion is effected as the heavier frac­tion moves to the outside and down the conical-shaped tank. The lighter fraction flows to the middle and is forced upwards and floated off; and the heavier fraction sinks to the bot­tom and is extracted, as seen in the diagram.

hydrostatic weighing method. The determination of the specific gravity of a gemstone or other substance by weighing it immersed in water and also in air. The S.G. is then stated as the ratio between the weight in air, and the loss of weight in water (i.e., the difference between the air and water weights). The general formula for specific gravity is:

weight in air

weight in air - weight in water

. See

diamond BALANCE, SPECIFIC GRAVITY, SPECIFIC-GRAVITY ATTACHMENTS.

Horatio diamond. A misnomer for rock crystal from Arkansas.

Hornby Diamond. Thought to have been brought to England from the East Indies by the Honorable William Hornby, Governor of Bombay, in 1775. It was reported by Streeter in 1882 to weigh about 36 carats. One writer of the nineteenth century ex­pressed the belief that it later came

into the possession of the Shah of Persia (Iran). Ownership has been denied by the Central Bank of Iran in Tehran, where the Crown Jewels are kept. However, Dr. V. B. Meen re­ported in 1966 that a 38.18-carat trapezoid-shaped diamond among the Crown Jewels of Iran could be the Hornby.

Hortensia Diamond. A lovely and unique peach-colored stone of 20 carats that was doubtless worn by Hortense de Beauharnais, Queen of Holland (1783-1837), who was the daughter of Empress Josephine, wife of Louis Bonaparte and mother of Napoleon III. The catalog of the Apollon Gallery, Louvre Museum, Paris, states that the stone was pur­chased by Louis XIV and that la­ter, after the robbery of the Royal Treasury in 1792, it was retrieved from its hiding place under a roof in Les Halles district. It is now on ex­hibition in the Louvre.

Hot-Springs diamond. A misnomer for rock crystal.

Howeson Diamond. A 24-carat sap­phire blue diamond reported in 1953

to be in the possession of the widow of the late John Howeson of London. There is no later report of it.

Hope diamond. The 45.52-carat, dark-blue Indian stone known as the Cutting history of the Hope Di'. Hope is undoubtedly one of the world's most celebrated Diamonds, although far from being the largest. The origin of the Hope Diamond has been highly speculative until re­cently. A study by H. Tillander (1975) of the dimension and weight figures from the stages of the cutting of the Tavernier Blue resulting in the Hope Diamond indicate that: (1) The Tavernier Blue had been recut three times to the present gem, the Hope; and (2) no other stones may possibly have resulted from any of the recut-ting operations. (See diagram of evolution of the Hope Diamond.) Past investigators believed that a similarity of color between the Hope and the 13.75-carat Brunswick Blue Diamond suggested that the two stones were the result of recutting the 69.03-carat French Blue Diamond. The French Blue, which was stolen from the Garde Meuble (French Royal Treasury) in 1792 and never recovered, was a "heart-shaped" stone. The Hope first appeared on the scene at the London market in 1830 and was purchased for the gem collection of Henry Philip Hope for $90,000. After Hope's death in 1839, the stone became the possession of

(Washington, D.C.), as a gift for his wife. Mrs. McLean's wealth came from the fabulously rich Camp Bird Mine near Ouray, Colorado. Despite the legends surrounding the Hope, including about a dozen violent deaths and disasters to two royal houses, she never considered the stone unlucky, even though her life was plagued by a number of per­sonal misfortunes. Following Mrs. McLean's death in 1947, Harry Winston, New York City gem mer­chant, purchased the famous stone for $179,920 and presented it to the Smithsonian Institution in Wash­ington, D.C., where it is on perma­nent exhibit. In 1962, it was one of the features of the Ten Centu­ries of French jewelry exhibition at the Louvre Museum, Paris, France. Note: At the suggestion of Dr. Her­bert Tillander, a recent reweighing (1975) of the Hope Diamond by Robert Limon, C.G., showed it weighed in at exactly 45.52 carats instead of the 44.50 carats as previ­ously reported in the literature. Hopetown. A town in Cape Pro­vince, Republic of South africa, and the location of minor alluvial dia­mond diggings. Current production is inconsequential. It was the lo­cation of the discovery of South Afri­ca's first diamond (1886).

high shoulders. A pear shape cut in such a way that the heel end of the

stone has a flattened appearance with square-shaped corners rather than a true semi-circular outline. This is usually done in order to retain more weight. See belly, head, heel,pear shape.

H.L.G.,

Ltd. A mining company that operates alluvial-diamond deposits in the Lichtenburg and Barkly West districts, Republic of South africa. It is a wholly owned subsidiary of De Beers Consolidated Mines, Ltd.

Hoffman, M. K. A German scientist who, in 1931, repeated the experi­ments of Moissan in an effort to pro­duce synthetic Diamonds, but with­out success. See moissan, Ferdinand

FREDERIC HENRI; SYNTHETIC DIAMOND.

Holland Diamond. A 36-carat conical-shaped diamond reported in the 19th century to be in the Crown Jewels of the Netherlands. It has never been authenticated. Present whereabouts unknown. Possibly, this is the Bantam Diamond seen in Java by Tavernier. See bantam diamond.

Holland Syndicate. A Dutch dia­mond-mining company that works al­luvial deposits in Ghana (Gold Coast), Africa. Annual production is approx­imately 200,000 to 250,000 carats. See

GHANA.

holohedral class (ho'-low-he"-dral).

See hexoctahedral class.

Holpan. A minor alluvial diamond deposit in the Barkly West area, Cape Province, Republic of South Af­rica. Production from these diggings amounted to less than 200 carats in one recent year.

Homansvlei. A minor alluvial dia­mond deposit in the Schweizer Reneke area, Transvaal Province, Re­public of South Africa. The yield from this digging in one recent year was less than 100 carats. Hondsriever. A minor alluvial dia­mond deposit in the Bronkhorst-spruit area, Transvaal Province, Repub­lic of South Africa.

Hope Diamond. The 45.52-carat, dark-blue Indian stone known as the

Hebron. A minor alluvial diamond deposit in the Barkly West area, Cape Province, Republic of South Af­rica. The total output in one recent year was less than 1400 carats.

heel. The rounded end of a pear-shaped stone opposite the point. See

PEAR SHAPE, BELLY.

Herbert. A town in Cape Province, Republic of South africa, and the lo­cation of minor alluvial diamond diggings.

Herkimer diamond. A misnomer for rock crystal from Herkimer Co., New York.

Hershey, Dr. J. W. An American in­vestigator who carried out research into the problem of diamond syn­thesis at McPherson College, Kansas, in 1938. By using a variation of the molten-iron process of Crookes and Moissan, he claimed to have pro­duced synthetic Diamonds, but there is no proof that his experiments were successful. In 1940, he wrote The Book of Diamonds, in which his method is discussed. See crookes, sir

WILLIAM; MOISSAN, FERDINAND FREDERIC HENRI; SYNTHETIC DIAMOND.

hexagon cut. A hexagonal (i.e., six-sided) form of cutting, usually step cut with all sides of equal length. hexoctahedral class (hex-ahk'-tah-he"-dral). A name given to the high­est symmetry class of the cubic, or isometric, crystal system. Diamond is in this class. Synonymous terms are holohedral class and normal class

(hex-ahk'-tah-he"-dron). One of the seven basic forms in the highest symmetry (hexocta­hedral) class of the cubic, or iso­metric, crystal system. It has 48 trian­gular faces, with each plane face in­tersecting all three crystallographic axes. Although there are a number of hexoctahedrons that differ in respect to the inclination of their faces, this form can be visualized as an oc­tahedron, with each of the faces hav­ing been replaced by six triangular faces. See cubic system, hexoctahedral

CLASS, OCTAHEDRON.

hextetrahedron. An isometric crystal form of tetrahedral symmetry having 24 similar faces with unequal inter­cepts of all three axes. See cubic sys­tem.

Higgshope. A minor alluvial dia­mond deposit in the Hopetown area,

heat treatment (of diamond). Heat­ing a diamond or other material at a given temperature for a specified period to permit a partial or com­plete readjustment of the atomic structure that was previously altered by some type of treatment. For example, an irradiated diamond that has turned green may be changed to other colors by heat treatment. See

CYCLOTRON-TREATED DIAMOND, PILE-TREATED DIAMOND.

heavy liquid. A high-density liquid that is used to determine the specific gravity of Gemstones. Gems float if their specific gravity is lower than the density of the liquid, remain sus­pended if it is the same as that of the liquid, or sink if it is higher than that of the liquid. The S.G. of diamond is 3.52. The most commonly used

liquids for testing gems are methy­lene iodide (S.G., 3.32), pare bromo-form (S.G. 2.89), diluted bromoform (S.G. 2.85) and bromoform diluted with xylene to a density of 2.62. A transparent liquid with a density of 3.52 may be made by diluting C/er/c/'s solution slightly with distilled water. See specific gravity.

heavy-media separation. A recovery method for Diamonds, based on the principle that an agitated suspension of finely ground solids in water be­haves as a heavy liquid. A suspen­sion with an effective specific gravity of 2.95 and the characteristics of a true heavy liquid is obtained by agi­tating the proper mixture of finely ground ferrosilicon and water. When crushed blue ground is fed into this

liquid, the diamonds and other dense materials settle to the bottom and the lighter materials remain suspended or rise to the top. By using this method, over 80% of the worthless material is separated from the dia­monds and other heavy particles. See

HEAVY LIQUID, SPECIFIC GRAVITY.

Hawaiian diamond. A misnomer for rock crystal.

head. A term sometimes used for heel, the rounded end of a pear-shaped stone opposite the end ter­minating in a point. See heel, pear shape.

head magnifier. A simple binocular magnifier that is worn on the head by jewelry repairmen and manufac­turers and by diamond and colored-

stone graders. Many diamond grad­ers believe that their efficiency in color grading is increased slightly by low magnification.

Heart Diamond. Tavernier, the French jeweler and traveler, saw this 35-carat heart-shaped brilliant mounted in an ornament in the trea­sure of Aurangzeb of India. Addi­tional details lacking.

. A heart-shaped variation of the brilliant cut that is related to the pear shape. The round end is flattened and indented and the girdle diameter across the shoulders is widened until the

diameter is approximately equal to the length.

heat conduction. Diamond has a very high thermal conductivity, the highest of any known material which is why they initially feel cold to the touch. Extremely heat-conductive Type I la stones are used as heat sinks to conduct heat away from materials or delicate instruments. heat, effect on diamond. Transparent diamond will burn in oxygen at about 800°C, with carbon dioxide as the product. In air (approximately 20% oxygen) the temperature of com­bustion is about 875°C, although a figure as low as 690°C. has been reported. Diamond will convert to graphite by heating it in a vacuum to between 1200°C. and 1900°C. At approximately 3700°C, in a non-oxidizing atmosphere under control­led conditions, theoretically the diamond would melt. The heat from a jeweler's torch may cause the sur­face of a diamond to become leaden and cloudy, but the condition can be corrected by repolishing. In exces­sive heat, greater than 800°C, the color may be removed from treated Diamonds. Excessive heat may also cause an undesirable color change in an irradiated diamond; e.g., a green cyclotron-treated stone. Rapid tem­perature changes may cause the de

velopment of internal imperfections or an increase in the number or size of cleavages or fractures already pres­ent, due to the unequal expansion of included minerals. A flawless diamond, however, suffers very little change of volume with change of temperature. Therefore, although care should be taken, sudden tem­perature changes are much less likely to cause cracks in diamond than in many colored stones. See

THERMAL EXPANSION (OF DIAMOND).

Harlequin diamond. An important part of the Wurttemberg Crown Jew­els, the 22-carat Harlequin Diamond was originally set in a Golden Fleece for Duke Karl Alexander (1733-1773). It is now set as a pendant in a three-row, 97-stonediamond necklace and is on display in the Wurttem­berg Landsmuseum, Stuttgart, Ger­many.

Harry Young Diamond. A 269.50-carat light yellow diamond octahed­ron discovered in 1913 on the Vaal River, Cape Province, Republic of South africa. Ultimate disposition unknown.

Hartebeestlaagte. A minor alluvial diamond deposit in the Ventersdorp area, Transvaal Province, Republic of South Africa. A production of less than 200 carats was reported for one 12-month period in the late 1950's.

Harvard Diamond. A near-perfect, 82-carat yellow octahedron was once part of the James A. Garland collection, Peabody Museum, Har­vard University, Cambridge, Mas­sachusetts. It was stolen in 1962 and never recovered.

Hastings Diamond. A political scan­dal ensued when this 101-carat diamond was presented to King George III in 1786 by Warren Hast­ings, Governor General of India, as a gift from the Nizam of the Deccan. Hastings, already under a cloud (la­ter impeached) for his inept ad­ministration of India, was accused of trying to bribe the King with the diamond. Further historical details lacking.

Hatton Garden. The center of the London diamond and wholesale jewelry district.

Haute-Guinea. Upper Guinea, the most important diamond-producing area in Guinea (formerly French West Africa). See guinea.

Haute-Sangha. The most important diamond-mining district in the Cen­tral African Republic. The principal company operating here is Compag-

nie Miniere de I'Oubangui Oriental (CMOO).

Halo Cut (trademark). See polished

GIRDLE.

Halphen diamond. Streeter gives the only known record of this diamond: "Almost the only specimen of Red Diamond is a gem of a carat weight, bought by the author and sold to the late Mr. George Samuel for £800." Alternate name Halphen Red Dia­mond. Halphen Red Diamond. See halphen

DIAMOND.

hand loupe. See loupe Hanger Diamond. A 123-carat pale yellow rough diamond found in the early days of the South African diamond rush. It was reportedly purchased by Capt. E. S. Hanger of the Bloemfontein Rangers about 1868. Hanger sent the stone to Amsterdam to be cut into a brilliant rose-cut gem. It was subsequently purchased by the Countess of Char-lemont from County Tyrone, Ireland in 1870 for £300 and deposited in a bank as a future investment. No other details are available. Hannay Diamonds. See hannay, james

BALLANTYNE.

Hannay, James Ballantyne (1855-1931). A Scottish chemist who, in 1880, claimed to have produced mi­nute diamonds by heating amor­phous carbon with bone oi I and metal­lic lithium under great pressure. At the time, there was no satisfactory method for proving or disproving Hannay's claims. Later efforts to du­plicate his experiments failed to pro-

SYNTHETIC DIAMOND.

hardebank. A harder-than-usual type of kimberlite, or blue ground. See

BLUE GROUND, KIMBERLITE, YELLOW GROUND.

hardness. The resistance of a sub­stance to being scratched. Diamond is 10 on Mohs scale of hardness. Tests prove that diamond is approxi­mately 10 to 150 times as hard as corundum, the next hardest mineral. The variation stems not only from differences obtained by different hardness-testing methods, but also from the fact that various directions on a given diamond's surface show a

habit. (1) The characteristic general shape of a crystal resulting from its internal structure and controlled by the environment in which the crystal grew. (2) The characteristic crystal form, including distinguishing ir­regularities, of a mineral. (3) Used to denote the general shapes of crystals; e.g., cubic, blocky, tabular, prismatic. Characteristic habits of diamond are usually octahedral, cubic, dodeca-hedral, and hexoctahedral, which may have somewhat rounded crystal faces and edges.

hailstone bort. A rounded type of bortthat differs greatly in appearance and structure from all other forms. Typically, it consists of alternating layers of gray to clear, poorly to well-crystallized minute diamond crystals. See bort.

hairline feather. See feather

half. A common abbreviation for a half carat.

half brilliant. Same as half-brilliant cut.

half-brilliant cut. A rarely used style of cutting that has a circular girdle outline, a flat, unfaceted base, and a standard brilliant-cut crown; i.e., 32 facets and a table. Also called half brilliant or brillionette. This cut isused principally to defraud, by set­ting in a gypsy-style mounting over foil arranged to simulate pavilion facets; thus, the stone appears much larger than it is.

Gunsons Sortex Limited. London manufacturer of machines for sorting seeds who developed an X-ray diamond sorting unit that was install­ed in several De Beers treatment plants. Concentrates are passed under an X-ray beam and when any diamond fluoresces, a photomulti-plier tube causes an air jet to deflect the stone into a diamond catch bin.

See X-RAY SEPARATOR.

Guyana. Formerly British Guiana in South America. The first discovery of Diamonds on the north coast of South America occurred in Guyana in 1890 in the gravels of the Maza-runi River, which is the largest pro­ducing region today. Of less impor­tance are the gravels of the Cuyuni, Puruni, Potaro and Berbice Rivers. Annual production is less than 50,000 carats, with about 60% of the total yield being industrial grade. Mining is done mostly by individuals or by two- or three-man crews using crude equipment. Diamond produc­tion in 1975 was reported to be 13,000 carats industrial and 8,000 carats gem quality. gypsy (gipsy) setting. Mounting in which the stone is deeply set into the metal so that the table facet is almost level with the metal surface. A popu­lar setting with diamonds in the 19th century; also, used with poor quality diamonds or diamond simulants.

grupiaras. A Brazilian term for dia­mond-bearing valley deposits.

Guenther, P. L. A German scientist who, in collaboration with two as­sociates, R Gessele and W. Reben-tisch, attempted to produce synthetic Diamonds in 1942 by utilizing spe­cial apparatus that permitted pres­sure up to 120,000 kilograms per square centimeter and temperatures as high as 3500°C. Numerous tests with multiple variations were carried out. The duration of the experiments varied as well as the method of quick cooling. In addition to pure melted iron, mixtures of iron with man­ganese, silicon, beryllium, lithium and nickel were used in conjunction with both coal and graphite. Of the few minute particles that were pro­duced, none was proven to be diamond. Guenther considered his experiments a failure. See synthetic

DIAMOND.

Guinea. Formerly French Guinea, a country in French West africa. A major producer of alluvial diamonds, particularly in Upper Guinea (Haute-Guinea), to the east of Sierra Leone and north of Liberia. Recorded exports have been much smaller than production, because much of the output has been smuggled into Liberia. Estimated diamond produc­tion for 1975 was 55,000 carats in­dustrial and 25,000 carats gem qual­ity. See FRENCH WEST AFRICA, KEROUANE.

Guise Diamond. A 28.44-carat rose-colored diamond reportedly purchased by Louis XIV in 1665 from his cousin, Marie of Lorraine. Previ­ously it had belonged to Henry, Duke of Guise, for whom it was named. The 1691 inventory of the French Jewels listed the Cuise at 33

carats. Later, by 1774, it had been recut into a rectangular shape weigh­ing 28.39 carats. Subsequently, it was stolen from the Garde Meuble in the great French jewel robbery of 1792. It was recovered and in the 1811 inventory it weighed 28.72 carats. The Guise was sold in 1888 and its weight listed as 28.44 carats. There is no later report of it and its whereabouts is unknown.

Griqualand West. An alluvial diamond-mining area in the Repub­lic of South africa; a division of Cape Province. The historic mining town of Kimberley is situated in this area.

Griqualand West Diamond-Mining Co. A diamond-mining company in the Republic of South Africa, control­led by De Beers Consolidated Mines, Ltd. This company owns the Du-toitspan Mine, comprising 512 claims, at Griqualand West, Cape Province.

grizzly. A screen used for sorting blueground at the diamond mines. 5-, 2- and iy4-inch screens are used.

Grodzinski, Paul. Until his death in 1957, one of the outstanding au­thorities in the industrial applications of diamond and other hard materials. He was head of the Industrial Diamond Information Bureau, editor and cofounder of the Industrial Diamond Review, and editor-in-chief of the Bibliography of Industrial Diamond Applications. For many years he was a member of the Educa­tional Advisory Board of the Gemological Institute of America. In addition to his many papers and arti­cles, he wrote Diamond Tools (New York, 1944) and Diamond Technol­ogy (London, 1953).

Grootdoorns. A minor alluvial dia­mond deposit in the Bloemhof area, Transvaal Province, Republic of South Africa. Annual production is negligible.

Grootlaagte. A minor alluvial dia­mond deposit in the Schweizer Ren-eke area, Transvaal Province, Repub­lic of South Africa. The annual yield from this mine is very low.

Grootpoort. A minor alluvial dia­mond deposit in the Schweizer Ren-eke area, Transvaal Province, Repub­lic of South Africa. The yearly yield from this mine is very low.

growth line. Lines which affect light in a manner that makes them visible as a banded effect within the stone, as well as on the surface. Under cer­tain lighting conditions, this banded effect usually is revealed parallel to octahedral faces, so that four sets of growth lines may be observed. Growth lines are hard to detect. See

POLYSYNTHETIC TWINNING, TWINNING LINES, KNOT LINE.

growth markings. The surfaces of crystals often have markings that are characteristic of the material. Diamonds show characteristic fea­tures for different crystal forms. Oc-tahedra usually show triangular de­pressions, called trigons, oriented in reverse to the orientation of the face on which they appear. Dodecahedra are usually grooved parallel to the long direction of each face, and cubes have square or rectangular depressions at 45° angles to the edges of the face. See trigon.

Great Star of africa diamond. See

CULLINAN (I) DIAMOND.

Great Table Diamond. A legendary stone, supposedly seen by Tavernier in the 17th century. It reportedly weighed 242 French carats, or 250 metric carats and its shape was flat and oblong, with one corner broken off. Also called White Tavernier Diamond and Table Diamond.

Great White Diamond. See victoria

DIAMOND.

Green Brilliant Diamond. A 40-

carat, green, brilliant-cut diamond, described by a writer in 1882 as hav­ing been worn by the King of Saxony (1697-1733) as a button in the plume of his hat. It should not be confused with the Dresden Green Diamond, a 41-carat pear-shaped stone. The Green Brilliant was on display in the Green Vaults of the Dresden Histori­cal Museum prior to being confis­cated by the Russians in 1945. It was subsequently returned to the Mu­seum in 1958.

green diamond. A naturally green, yellowish-green, apple-green or olive-green diamond of a sufficiently pronounced color to be an asset. Such a stone is called a fancy. Fine green stones are extremely rare. Some have been described as emerald green, but it is doubtful if this color exists. The 41-carat Dres­den Green Diamond has been de­scribed as an emerald-green stone, but it is actually yellowish green. A stone turned green by emanations from radium, a cyclotron or a ra­dioactive pile should not be called a green diamond without being pre­ceded by a descriptive term or terms to show the origin of the coloration. Many green Diamonds of a lighter tint are mined, particularly in Sierra Leone.

Green Dresden Diamond. See Dres­den GREEN DIAMOND.

Grima

Diamond. A 55.91-carat pear-shaped diamond, reportedly of "fine white" color and "internally flawless," was purchased in No­vember, 1972 by Andrew Grima at the Christie's sale in Geneva.

Greater Namaqualand. See namaqua-

LAND.

Great Harry diamond. A large (exact size unrecorded) lozenge-shaped diamond that was part of the Scottish Crown Jewels that James VI took with him when he became James I of England. At the time (about 1605), he had it mounted with other gems in a jewel known as the Mirror of Great Britain. There is no trace of this diamond today.

Great Mogul Diamond. Found in India in the middle of the seven­teenth century, the Great Mogul is said to have weighed 787.50 carats in the rough. It was among the trea­sures of the famous Shah Jehan, builder of the Taj Mahal and owner of the Koh-i-Noor. He ruled a power­ful empire just north of Golconda, in India, where Diamonds were first discovered. Aurangzeb, the son of Shah Jehan, showed the great gem to the French traveler and gem expert, Tavernier, presumably the only Euro­pean to see it. Tavernier, who said it resembled "the half of an egg cut through the middle," published a picture of it, from which all known

replicas have been made. The Great Mogul was a rose-cut stone and weighed only 280 carats, according to Tavernier's reckoning, at the time he saw it. He was told that Hortensio Borgio, a Venetian who cut the stone from the original 787.50-carat rough, did such a poor job that the Mogul refused to pay him; rather, he fined him 10,000 rupees, his entire for­tune. The further history of the stone is unknown, but it is believed to have been among the loot carried off by the Persians after the sack of Delhi in 1739. Curiously, the descrip­tion of the Orloff closely resembles that of the Great Mogul, except in weight, and some experts think that it is the same stone and that Taver­nier may have miscalculated in trans­lating the Indian rati, or diamond weight (1.87 grams), into the Euro­pean standard, the carat.

Grao Mogol. A former diamond producing region in Minas Gerais, Brazil. This district was soon worked out, but in 1839 approximately 2000 garimpeiro were engaged in mining. graphite. A polymorph (allotrope) of elemental carbon. It occurs in tabu­lar crystals of hexagonal outline with a prominent basal plane usually in foliated or scaly masses. Graphite's structure consists of carbon atoms forming flat hexagonal sheets of six-membered rings with-loose bonds between sheets (3.25 A units apart whereas in diamond the closer 1.42 A units is far stronger), consequently graphite is very soft. Cleavage is parallel {0001}, hardness 1-2, black color, black streak, metallic luster, greasy feel, specific gravity 2.09-2.23, melting point about 3,500°C, an electrical conductor. Usually found in metamorphic rocks. See

DIAMOND, LONSDALEITE.

Grasfontein. One of the more impor­tant alluvial diamond deposits in the Lichtenburg area, Transvaal Province, Republic of South africa. Production

for a recent year was about 3800 carats. In 1927, it was the scene of one of the greatest rushes in dia­mond-mining history; it was also one of the most orderly and spectacular.

Graspan. A minor alluvial diamond deposit in the Schweizer Reneke area, Transvaal Province, Republic of South Africa. The yearly yield from this mine is very low.

grease belt. An endless, grease-coated belt that utilized the same principle as the grease table for the recovery of Diamonds. Grease belts have largely superseded grease ta­bles. See GREASE TABLE.

grease table. A device for separat­ing diamonds from other heavy min­erals after concentration of crushed blueground. Since water does not adhere to the surface of a clean diamond, diamonds adhere to the grease. Other minerals are wetted and are washed over the slanted rocking tables. See kirsten, f. b.

greasy luster. See luster.

grain. (1) One-quarter of a metric carat (0.0500 grams or 0.25 ct.), a unit of weight commonly used for pearls and sometimes for other gems. (2) Cleavage, sawing or polishing di­rections in diamond. When used alone, the word grain usually refers to the cleavage direction, but may refer to sawing and polishing direc­tion. See CLEAVAGE (IN DIAMOND), CUBE, DODECAHEDRON, POLISHING, SAWING.

grainer. Stones with weights near multiples of 0.25 ct., or one grain, are referred to as grainers, qualified by the appropriate numerical desig­nation; e.g., four-grainer for a one-carat stone.

grain line. See twinning line.

Grand Conde Diamond. See le

GRANDE CONDE DIAMOND.

Grand Duke of Tuscany Diamond.

See FLORENTINE DIAMOND.

Gran Sabana. One of the important diamond fields in Venezuela. See

VENEZUELA.

grao. A Brazilian weight for dia-

monds and other gems; the equiva­lent of about Vi carat.

Goniometer. An instrument used to measure the angles between crystal faces.

Goniometer contour print. A photo­graph of light points reflected from the crown facets of a faceted stone (diamond). See identigem.

Good Hope. A minor alluvial dia­mond deposit in the Barkly West area, Cape Province, Republic of South africa. Annual production from the diggings here is negligible.

Good Hope Diamond. See star of Per­sia DIAMOND.

goods. Mining companies, marketers of rough, cutters, importers and wholesalers, often refer to categories of their diamond merchandise as goods. See close goods, common goods,

GRADED GOODS, LOOSE GOODS, MOUNTED GOODS, OUTSIDE GOODS, POLISHED GOODS, SAWED GOODS, WHOLE GOODS.

Gordon Diamond. A slightly yellow 30-carat rough diamond crystal was reportedly discovered by a Belfast land surveyor between 1862 and 1866 in South Africa. Among other geological specimens that he brought back to Ireland in 1866 was a piece of fibrous quartz in which was em­bedded a crude diamond. A Belfast jeweler noticed the diamond and sent it to Antwerp for evaluation. Its history after cutting is unknown. Like the Platberg and Charlemont Dia­monds, this diamond's discovery pre­cedes that of the Eureka Diamond.

Gordon Orr Diamond. A 62-carat rough diamond of exceptional qual-

ity that was found in the Wajrah Karur Mines, Bellary District, India, in 1883. It was cut into a 24.85-carat brilliant. The present location of this stone is not known.

gorgulho. A Brazilian term for frag-mental diamond-bearing material as­sociated with clay in plateau de­posits. See cascalho.

Gornyak Diamond. The Gornyak rough reportedly weighs 44 carats and is valued at 100,000 rubles. It was found in Yakutiya, Siberia and presently is in the Russian Diamond Fund, Moscow. Governador Valladares Diamond.

See BENEDITO VALLADARES Diamonds I, II, AND III.

Government Diamond Office (Sierra Leone). A Sierra Leone government diamond buying, selling, and market­ing organization managed by Dl-CORWAF. GDO was established in 1959.

Goyaz Diamond. A Brazilian dia­mond that was found on the Ver-issimo River, State of Goyaz, in 1906. Existing records, which are vague and incomplete, indicate that the rough weighed 600 carats and that one of its cleavage fragments was fashioned into an 80-carat stone. No additional information is available.

graded goods. Diamonds that have been graded by the cutter, importer or wholesaler before sale to the re­tailer, in contrast to melange offering. See goods, melange.

Graduate Gemologist. One who holds the Graduate in Cemology Diploma, awarded by the Gemologi-cal Institute of America, after suc­cessful completion of either its cor­respondence or full resident courses

Golconda d'Or diamond. Consid­ered to be the largest emerald-cut golden diamond in the world, this historical stone was recut by Asscher of Amsterdam from its original 130 carats and now weighs 95.40 carats. The Golconda d'Or is notable be­cause it is one of the last large Diamonds taken from the old Gol­conda Mines of India. First men­tioned in 1739 as part of the booty taken from Delhi by the Persian in­vader Nadir Shah, it reportedly was later handed down to the Sultan of Turkey in the early 19th century. In 1909, the first President of the Turkish Republic, Mustafa Kemal Ataturk, sold the Golconda d'Or to a wealthy Turkish family. It was later purchased by Dunklings, the Jewelers, Mel-

bourne, Australia, in 1962, where it is now on permanent display.

Gold Coast. See ghana.

Golden Dawn Diamond. Found in 1913 on the Vaal River, Cape Pro­vince, Republic of South africa. 133 carats. Cut to a 61.50 brilliant. Auc­tioned in 1926 to the Aga Khan for $24,000, in whose family it presum­ably remains today. Golden Maharaja. A fine quality of golden color pear-shaped diamond, weighing 65.60 carats. The Golden Maharaja attracted international at­tention at the 1937 World's Fair in Paris for its beauty and, especially, the unusual color.

Golden Pelican Diamond. Aptly named for the Pelikaanstraat, An­twerp's famous diamond center, where it was cut and polished, the 64-carat, golden, emerald-cut Co/d­en Pelican has been exhibited in Canada and Switzerland and in 1958 at the Diamond Pavilion at the Brus­sels World's Fair by its owners, E. Severy and M. Ginsburg of Antwerp. It was valued by the owners at $50,000.

Gong Gong. One of the early diamond diggings on the Vaal River,

Cape Province, Republic of South Af­rica. Now an insignificant producer, the Gong Gong diggings produced only approximately 600 carats in one recent year.

glazier's diamond. Bort or small fragments of diamond crystals for cutting glass.

glets (or glatts, glatze, gletz). A word of Dutch origin for a feather in a diamond. It is a cleavage crack that looks like a feather. See feather.

gletsen. Plural of glets.

Goa. A city in India through which the Portuguese imported Brazilian Diamonds in the early part of the 18th century to suggest Indian origin. After the discovery of diamonds in Brazil in 1725, they were difficult to sell. The European and Indian mer­chants feared that the sudden influx of Brazilian stones on the market would cause prices to drop, so they claimed that the stones were "too hard to cut" or that they were actu­ally inferior Indian diamonds that had been shipped to Brazil to fool buyers. Probably a number of other yarns were concocted. The Brazilian dealers neatly offset this difficulty by shipping the diamonds by way of the Indian port of Goa and selling them as Indian stones.

Godavari River. A river in Hyder­abad and Madras, India. At one time a source of diamonds.

Goedehoop. A minor alluvial diamond deposit in the Christiana area, Transvaal Province, Republic of South africa. The annual yield from this deposit is inconsequential.

Goedgedacht. A minor alluvial diamond deposit in the Ventersdorp area, Transvaal Province, Republic of South Africa. A production of less

than 200 carats was reported for one recent year.

Goedvooruitzicht. A minor alluvial diamond deposit in the Lichtenburg area, Transvaal Province, Republic of South Africa. Total production for one recent 12-month period was only 364 carats.

Goias. A minor diamond-producing state in Brazil. See brazil.

Goias Diamond. A 600-carat rough discovered early in 1906 along the Verissimo River, Goias, Brazil. Re­ported to have been discovered by an old man who was neither knowl­edgeable as a prospector nor in gem testing procedures. The diamond was later shattered by a blow from a hammer since diamonds were gen­erally believed by some to be inde­structible. Later, two fragments were identified as diamond. It is believed that the original crystal size was comparable to a box of matches or weighed possibly in excess of 600 carats. The original crystal was de­scribed as very deformed. From the two remaining fragments only one stone of approximately 8 carats was cut.

Golconda. (1) The name of a city in India that was the center of the diamond trade in the 17th century. (2) A name used to refer to the an­cient alluvial-diamond deposits to the south and east of the city of Gol­conda along the Pennar, Kistna and Karnul Rivers; also referred to as the Kistna Croup. See Hyderabad, india. (3) A color grade that is seldom used to­day. It refers to a highly transparent (limpid) stone, either entirely without body color or with a faint bluish cast.

Golconda Diamond. A 30-carat emerald cut diamond of fine color and clarity which was for many years

in the "Collection of Registered His­toric Gems" of Trabert & Hoeffer, Inc., New York City jewelers. Their description calls it "one of the last large diamonds from the old Indian Mines." It was purchased by R. J. Reynolds, tobacco millionaire, in 1960, for $70,000 and given to Muriel Greenough, who became the third Mrs. Reynolds.

girdling (also called rounding up, bruting or cutting). The step in the fashioning process of a diamond in which the stone is given its circular shape. The stone is held in a lathe, or cutting machine, and another dia-mond, called a sharp or tool stone, which is affixed to the end of a long dop that is supported by the hands and under an armpit, is brought to bear against the stone being shaped. An older method con­sisted merely of rubbing two Diamonds together until the desired shape was obtained. glanzloserdiamant. German, mean­ing a cloudy diamond; a dull sur­face; without luster.

glass. An amorphous substance pro­duced by the fusion of oxides at high temperatures that can be manufac­tured to have a range of physical properties. There are two principal types of glass, the crown glasses, made of silica, potash, soda, and lime; and the flint glasses with lead oxide replacing the lime of the crown glass. The flint or "lead" glass, especially when thallium com­pounds are added, is the most impor­tant. Because of its high dispersion and brilliance, lead glass is a com­mon substitute for diamond and other Gemstones. See paste. mines for well-shaped, clear transpa­rent diamond crystals of good color with bright faces and without visible inclusions. (2) A term sometimes used to refer to a fashioned diamond that lacks brilliancy.

girdle area. See girdle

girdle facet. Small, plane or approx­imately plane, polished surfaces which are placed upon the girdle.

girdle (or break) facets. The 32

triangular facets that adjoin the girdle of a round brilliant-cut stone, 16 above and 16 below. Also called upper- and lower-break facets, upper- and lower-girdle facets, top-and bottom-half facets, skew facets, skill facets, or cross facets. Facets are also sometimes placed directly on the girdle, in which case the stone is usually said to have a faceted girdle.

See BRILLIANT CUT (ROUND), POLISHED GIRDLE.

girdle plane. A plane passing through the girdle of a stone separat­ing the crown from the pavilion.

girdle reflection. Reflection of the girdle as seen in the internal surface of the pavilion facets when viewed through the table.

girdle thickness. The width of the out­er edge, or periphery, of a fashioned diamond or other gemstone. In a rounded style of cutting such as the round brilliant, pear shape or marquise, the girdle edges, when viewed parallel to the girdle plane, consist of undulating lines caused by the intersection of the flat fac­ets with the curved girdle. In such stones, the girdle thickness is mea­sured across the midpoints of oppos­ing upper- and lower-girdle facets. In well cut stones, this dimension is suf­ficient to prevent this narrower por­tion of the girdle from being knife edged, but it does not exceed 1 % of the girdle diameter in stones of ap­proximately 0.50 to 2.0 carats. In smaller stones, the relative thickness is greater; in larger stones, smaller. Essentially, the girdle should appear

Ghana diamond Corp. One of the

companies in Accra, Ghana, that is licensed by the government of that country to buy Diamonds from native miners. See ghana.

GIA (Gemological Institute of America) Color-Grading System. A color-grading system for colorless to yellow diamonds that utilizes the let­ters D through Z for a colorless-to-yellow scale. These grades are set in relation to a series of master dia­monds thatare maintained in the

GIA's Los Angeles Laboratory. This range of the alphabet was purposely chosen to avoid confusion with the numerous trade systems employing letters starting at the beginning of the alphabet. See chart in Appendix enti­tled, Comparison of Several Different Diamond Color Grading Systems. See also color grade, master (or keyi

diamonds.

GIA Color Grader. An accessory in­strument designed and manufactured by the Gemological Institute of America to facilitate the color grad­ing of diamonds under binocular magnification and to demonstrate it readily to customers.

GIA Diamond Grader. A gemologi­cal microscope designed and man­ufactured by the Gemological Insti­tute of America. It consists of a binocular microscope mounted on an illuminator base and is equipped with a mechanical stoneholder, iris-diaphragm light control, light-and-dark-field illumination, tiltback, and a turntable. Accessories for propor­tion and color grading extend its use.

GIA Jewelers' Camera. Predecessor of the Photostand. See photostand. girdle. The outer edge, or periphery, of a fashioned stone; the portion that is usually grasped by the setting or mounting; the dividing line between the crown and pavilion. On step-cut diamonds, on almost all fancy bril­liant cuts, and on some round brilliant-cut diamonds the girdle is polished. On brilliant-cut styles, the polished girdle may or may not be faceted. An unpolished girdle surface should be so smooth that it has a waxy luster. See bearded (or fuzzy) gir­dle, BRILLIANT CUT (ROUND), GIRDLE THICKNESS, KNIFE-EDGED GIRDLE, LUMPY GIRDLE, POLISHED GIRDLE, GIRDLE PLANE, WAVY GIRDLE.