Indicolite is the blue sodium-rich variety of Tourmaline, and may come in all shades of blue, from light-blue, violet-blue to deep red or deep green. ...
Iolite is the violet-colored variety of Cordierite (named after French geologist P. Cordier), a silicate of aluminum and magnesium, with an orthorhomb...
Ivory is an organic gem material, largely obtained from the tusks of African and Indian (Asiatic) elephants, but also from the teeth and tusks of the ...
Jadeite is a silicate of sodium and aluminum, and is a member of the Clinopyroxene group of minerals. It is so called because it is the source of one ...
Jasper is the opaque form of Chalcedony, the microcrystalline varieties of quartz that form concretionary deposits, partially of organic origin in the...
Jet is an organic gem material composed of lignite, and is a bituminous coal which can be polished. It is compact, homogeneous, has a hard, glossy sur...
Kornerupine is a rare magnesium aluminum borate silicate which occurs as transparent prismatic crystals of the orthorhombic system. It is hard and a ...
Kunzite is the pinkish lilac variety of the spodumene. These crystals or stones have a light pink hue because they constrain, traces manganese. Kunzit...
Kyanite is an aluminum silicate that occurs as elongated and tabular in groups of light-blue crystals darker toward the center, or flat, bladed crysta...
Labradorite is a sodium-rich plagioclase feldspar which displays a particular type of iridescence on a dark ground. Plagioclase feldspars are rock-for...
