I1, I2, I3, Included, Imperfect | I1, I2, and I3 are all grades in the GIA clarity scale.
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IDB, Illicit Diamond Buying | In South Africa there is a law prohibiting 'Illicit Diamond Buying' or IDB. Any rough diamond found on public land must be sold to the government who resells it to De Beers.
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Ideal, Ideal Cut | Theoretically perfect cutting proportions for (round brilliant cut) diamonds. Exact specifications vary. Many mathematical models ignore girdle thickness.
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IGI, I.G.I., International Gem Laboratory | Organisation with laboratories located in the heart of the gem & jewelry districts throughout the world, including New York, Antwerp, Mumbai, Bangkok and Tokyo.
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Illusion | A style of setting making a diamond appear larger than it is, usually by setting into "white" gold, rhodium plating, and diamond cutting the surrounding area of metal.
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ImaGem | ImaGem Inc. is a manufacturer of equipment for grading diamonds by colour, clarity, carat weight, cut, brilliance, intensity, sparkle, and fluorescence.
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Imitation | Anything other than diamond which imitates diamond. Other words used include simulant and fake. It is important to note that synthetic diamond is real diamond. An imitation can be natural or synthetic.
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Imperfect, Imperfection, I | Clarity grading term.
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Incident Ray | The name of a ray of light as it enters a diamond, or change of medium.
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Included | Possessing inclusions, mainly internal features which impair the brilliance or clarity of a diamond.
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Inclusion | An internal feature or imperfection which reduces the clarity or brilliance of a diamond.
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Incomparable | A large diamond weighing 890 carats in its rough state, 407.48 carats polished, the third largest diamond ever cut.
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India | Until the discovery of diamonds in Brazil about 1730, India was the only known source. All known Indian diamond sources are now depleted and uneconomic, but India is now an important cutting centre, mainly because of low labour costs. The first known reference to diamond is a Sanskrit manuscript, the Arthsastra ("The Lesson of Profit") by Kautiliya, a minister to Chandragupta of the Mauryan dynasty in northern India.
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Industrial | Low grade or very small diamonds which are used as abrasives or other industrial purposes.
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Information | Facts and data. It is important to distinguish information from propaganda, which is essentially skewed or distorted information. Most salespeople, for example, will offer information which is limited and selected to optimise their chance of selling to you.
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Integrity | Integrity is important in most business to business markets, and the commercial diamond market is said to operate with integrity. Some proponents of the Kimberley Process speak about the integrity of diamond itself, as though this had ever been questioned. What they presumably mean is that there is a perceived threat to the welfare of the diamond industry by peace activists.
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Internally Flawless, IF, I.F. | A clarity grade which allows for naturals or other surface features or imperfections.
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International Diamond Manufacturers' Association, IDMA, I.D.M.A. | The International Diamond Manufacturers' Association was formed at the end of World War II, and first met in Antwerp in 1946.
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In the Rough | "Diamond in the rough" is an expression meaning somebody or something having exceptionally good qualities or the potential for greatness but lacking polish and refinement.
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Investment | Although a diamond purchase may prove to become a good investment. Our advice is to buy diamonds for the pleasure they invoke by their ownership and use. Because diamonds are not a homogenous commodity, the secondary market in them is not particularly liquid, compared with that for any other commodity.
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Investment Trust | In 1952 De Beers formed the De Beers Investment Trust, to hold the significant portfolio of industrial, gold and related mineral, and agricultural interests that the company had built up to diversify its income streams.
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Iron | Iron is used as a solvent and catalyst in the production of synthetic diamonds.
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Irradiated | A diamond which has been subject to radiation, usually to improve its colour. Most processes are kept as commercial secrets, but no residual radiation is retained by the treated stone.
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Isomer | Diamond is one of the isomers of carbon. Isomers are molecules which have the same molecular formulae but different molecular
structures.
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Isotropic | Being singly refractive, the opposite of doubly refractive (bi-refringent or anisotropic). Diamond is normally isotropic, but can be bi-refringent because of inclusions or internal strain.
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Israel | Israel is a leading centre for diamond trading and cutting, probably originating in the portability of diamonds, and the fact that many Jewish populations have faced upheavals and displacement. Jews form a major part of the world diamond trading and cutting industry.
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There are currently over 600 entries in this table.
Over 90 of them have page links to a page on this site. Eventually, we intend to add a more complete description for most entries, each on its own page.
Please watch this space!