All species of garnet possess similar physical properties and crystal forms but differ in chemical composition.

The different species are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite.

[5] Hessonite garnet is also named 'gomed' in Indian literature and is one of the nine jewels in Vedic astrology that comprise the Navaratna.

[7][8][9][10] Garnet species' light transmission properties can range from the gemstone-quality transparent specimens to the opaque varieties used for industrial purposes as abrasives.

[3] Garnets do not have any cleavage planes, so, when they fracture under stress, sharp, irregular (conchoidal) pieces are formed.

[14] For gem identification purposes, a pick-up response to a strong neodymium magnet separates garnet from all other natural transparent gemstones commonly used in the jewelry trade.

[15] Almandine, sometimes incorrectly called almandite, is the modern gem known as carbuncle (though originally almost any red gemstone was known by this name).

The name Almandine is a corruption of Alabanda, a region in Asia Minor where these stones were cut in ancient times.

[17] Almandine occurs in metamorphic rocks like mica schists, associated with minerals such as staurolite, kyanite, andalusite, and others.

[16] Pyrope (from the Greek pyrōpós meaning "firelike")[3] is red in color and chemically an aluminium silicate with the formula Mg3Al2(SiO4)3, though the magnesium can be replaced in part by calcium and ferrous iron.

Pyrope and spessartine gemstones have been recovered from the Sloan diamondiferous kimberlites in Colorado, from the Bishop Conglomerate and in a Tertiary age lamprophyre at Cedar Mountain in Wyoming.

[20] A variety of pyrope from Macon County, North Carolina is a violet-red shade and has been called rhodolite, Greek for "rose".

[3] It occurs most often in skarns,[3] granite pegmatite and allied rock types,[23] and in certain low grade metamorphic phyllites.

[26] Andradite is a calcium-iron garnet, Ca3Fe2(SiO4)3, is of variable composition and may be red, yellow, brown, green or black.

This is a rather rare garnet, bright green in color, usually found as small crystals associated with chromite in peridotite, serpentinite, and kimberlites.

Besides silicon, a large number of elements have been put on the C site, including germanium, gallium, aluminum, vanadium and iron.

[41] Lutetium aluminium garnet (LuAG), Al5Lu3O12, is an inorganic compound with a unique crystal structure primarily known for its use in high-efficiency laser devices.

[42] LuAG is particularly favored over other crystals for its high density and thermal conductivity; it has a relatively small lattice constant in comparison to the other rare-earth garnets, which results in a higher density producing a crystal field with narrower linewidths and greater energy level splitting in absorption and emission.

[43] Terbium gallium garnet (TGG), Tb3Ga5O12, is a Faraday rotator material with excellent transparency properties and is very resistant to laser damage.

[citation needed] The mineral garnet is commonly found in metamorphic and to a lesser extent, igneous rocks.

[46] The composition that is stable at the pressure and temperature conditions of Earth's mantle is pyrope, which is often found in peridotites and kimberlites, as well as the serpentines that form from them.

Mezger et al. (1992) conducted their own Sm/Nd investigation using hornblende and the drilled core of a 50 cm garnet to produce an isochron age of 1051 ± 4 Ma.

Connelly (2006) utilized seven different fractions of a Gore Mountain garnet to obtain a Lu-Hf isochron age of 1046.6 ± 6 Ma.

This is also the local age of peak metamorphism in the 1090–1040 Ma Ottawan phase of the Grenvillian orogeny and serves as a critical data point in ascertaining the evolution of the megacrystic garnet deposits.

Thousands of Tamraparniyan gold, silver and red garnet shipments were made in the old world, including to Rome, Greece, the Middle East, Serica and Anglo Saxons; recent findings such as the Staffordshire Hoard and the pendant of the Winfarthing Woman skeleton of Norfolk confirm an established gem trade route with South India and Tamraparni (ancient Sri Lanka), known from antiquity for its production of gemstones.

The garnet, as it is mined and collected, is crushed to finer grains; all pieces which are larger than 60 mesh (250 micrometers) are normally used for sand blasting.

These crystals are crushed in mills and then purified by wind blowing, magnetic separation, sieving and, if required, washing.

Both the river and the beach garnet suffer from the tumbling effect of hundreds of thousands of years which rounds off the edges.