I.D. bracelet: I.D. is short for "Identification", so an I.D. bracelet is simply a curved plate engraved with the name or initials of the person wearing it.

IGI: Stands for the "International Gemological Institute". It is the largest independent gem certification and appraisal service in the United States.

Igneous: A substance produced under conditions involving intense heat, such as that which is found in volcanoes. Igneous rock is rock formed by solidification from molten magma.

Import: The act of bringing or carrying in goods from an outside source for trade or sale, especially in regards to goods from a foreign country.

Inclusion: A naturally occurring flaw, (feather, fracture, fissure, carbon spot, or cloud), within a diamond or other stone. The test for clarity looks for these flaws.

Indicolite: Blue Tourmaline.

Ingot: Metal cast into a bar or other shape.

Inlaid: Past tense of inlay.

Inlay: A decorative technique in which part of the surface of a piece of jewelry, furniture, or ceramic is cut away and stone, mother of pearl, or some other substance is imbedded into the hollowed-out area so that it is level with the surface of the piece. See also channel inlay.

Intaglio: Italian for "carving", an Intaglio is a carved gem wherein the design is engraved or carved into the object so that it sits below the surface plane of the material, as opposed to a cameo in which the design is raised from it's background, in relief. This technique was often used for seals, which made a raised impression in wax used to seal a letter or authenticate a document. It was commonly attached to watch fobs, since the watch fob is a good manner of carrying a seal. Once seals fell out of common use, the intaglio tended to face out to the viewer rather than down as on a seal. Some of the most commonly found Victorian intaglios were carved in carnelian, an orange-brown variety of chalcedony.

Invisible Set: A method of setting square gemstones side by side in two or more rows within a metal border or frame so that they are flush against one another with no metal separating them.

Iolite: (also called dichroite or water sapphire). A silicate of alumina, iron, and magnesia which is usually violet-blue, but can be deep blue, light blue-gray, and yellow-white. Makes a beautiful transparent gemstone which is remarkable for its dichroism.

Iridescent: A display of lustrous rainbow-like colors. The colors seen in an oil slick or mother of pearl are good examples of iridescence. Synonymous with "Pearlescent".

Iridium: A metal of the platinum family often alloyed with platinum to improve workability. Pieces marked "80% Plat. 20% Irid" would indicate that the alloy is 80 % platinum and 20% iridium.

Iron: The most common metallic element which usually appears dark brown, from oxidation or impurity, but when pure is silvery-white. Iron is found abundantly in nature, usually in combined forms such as hematite, limonite, magnetite, and taconite. It is frequently alloyed in a wide range of important structural materials like cast iron, steel, and wrought iron. It is easily oxidized (rusted) by moisture, and is attacked by many corrosive agents.

Iron Pyrite: See Pyrite.

Irradiation: The process of bombarding a gemstone with X-rays, gamma rays or streams of subatomic particles in order to change the stone's color.

Ivoride: See French Ivory.

Ivorine: See French Ivory.

Ivorite: See French Ivory.

Ivory: A hard, smooth yellowish-white substance made from the tusks of elephants and walruses.

Ivory, French: See French Ivory.

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