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.
Intaglio: Carved gem where the design is created by incising into the stone making a negative pattern. When pressed into wax or clay the design would be raised. Itaglio rings were used to seal wax over a letter with the person's crest. Reverse intaglio is when an image is carved on the flat side of a cabochon so you can see the image through the front.
Invisible Cut: When a stone is cut on the surface so that is appears that there are multiple stones.
Invisible Setting: Invisible setting is a style in which rows of square princess cut diamonds or other gemstones rest perfectly flush against one another within a metal border or frame, with no metal separating them. This enhances the sparkle of a stone because no prongs or other metal is visible.
Iridescent: A display of lustrous rainbow-like colors. The colors seen in an oil slick or mother of pearl are good examples of iridescence
Ivory: A hard, smooth yellowish-white substance made from the tusks of elephants and walruses. There are different laws for different types of ivory depnding on whether the animal us endangered or not. Estate African elephant ivroy can be sold within the US, but Asian elephant ivory cannot be bought, traded, sold, imported or exported in the US.