January - Garnet

Garnet, the January birthstone, derived its name from the Latin word granatus, meaning like a grain, which refers to the mode of occurrence wherein crystals resemble grains or seeds embedded in the matrix.

Garnet is a family of minerals having similar physical and crystalline properties. They all have the same general chemical formula, , where A can be calcium, magnesium, ferrous iron, or manganese, and B can be aluminum, ferric iron, or chromium, or in rare instances, titanium.

The transparent purple to violet variety of the mineral. Amethyst is rare in the deep colors that characterize fine quality. It is usually colored unevenly and is often heated slightly in an effort to distribute the color more evenly. Heating at higher temperatures usually changes it to yellow or brown (rarely green), and further heating removes all color. The principal sources are Brazil, Arizona, Uruguay, and Russia.

Pale greenish blue or bluish green variety of beryl that is valued as a gemstone. The most common variety of gem beryl, it occurs in pegmatites, in which it forms much larger and clearer crystals than emerald, the dark green variety of beryl. Aquamarine occurs in Brazil, which is the chief source, and in such other sites as the Ural Mountains, Madagascar, Sri Lanka, India, and Maine, New Hampshire, Connecticut, North Carolina, and Colorado in the U.S. Heat treatment is commonly used to improve the colour of gem beryls.

The diamond is the hardest natural substance known. It is found in a type of igneous known askimberlite. The diamond itself is essentially a chain of carbon atoms that have crystallized. The stone's unique hardness is a result of the densely concentrated nature of the carbon chains. Like other igneous rocks, kimberlite was formed over the course of thousands of years by volcanic action that occurred during the formation of the earth's crust.

Kimberlite is located inside these former spheres of volcanic activity—often near mountain ranges—in vertical shafts that extend deep inside the earth. Inside the kimberlite areintermittent deposits of diamonds, one of several minerals present. However, not all kimberlite contains diamond. Other stones often found with diamonds are mica, garnet, andzircon. Kimberlite may be blue-grey in hue—thus termed blue ground—or if exposed to air it may have a yellowish cast and is called yellow ground.

One of the most highly esteemed precious stones, known to ancient Egyptians, Hindus, Greeks, and Romans. In India emeralds were used to adorn images in temples, and Moslems used emeralds as amulets, inscribed with verses from the Koran.

Emeralds were believed to change color when surrounded by deception and treachery. They were also believed to be preservatives against decay, dysentery, and the bites ofvenomous creatures and to promote easy childbirth. In ancient Rome the emperor Nero was said to have had an unusually large emerald that he used for viewing gladiatorial contests. Presumably he wasshortsighted and used it as a lens.

Native Americans of the Atlantic Coastal areas and the Mississippi River Basin were the first to collect and use U.S. freshwater mussel pearls and shells. Pearl pendants and ear pendants were worn by both sexes and both pearl and shell were used for decorative purposes on articles of clothing.

Some of the tribes used pearls as tributes, reportedly Powhattan (Pocahontas' father) had large stores of pearls received as tribute. Additionally, armlets, pendants, and gaming pieces were made from mussel shell.

The red variety of the mineral corundum, in its finest quality the most valuable of gemstones. Only medium to dark tones of red to slightly violet-red or very slightly orange-red are called ruby; light reds, purples, and other colors are properly called sapphires. In its pure form the mineral corundum, with composition Al2O3, is colorless. The rich red of fine-quality ruby is the result of the presence of a minute amount of chromic oxide. The chromium presence permits rubies to be used for lasers producing red light.

The finest ruby is the transparent type with a medium tone and a high intensity of slightly violet-red, which has been likened to the color of pigeon's's blood. Star rubies do not command comparable prices, but they, too, are in great demand. The ruby was among the first of the gemstones to be duplicated synthetically and the first to be used extensively in jewelry.

Peridot is the best known gem variety of olivine, a species name for a series of magnesium-iron rich silicate minerals. This bright yellow-green to green gemstone has caught the fancy of humans for thousands of years. Some historians even suspect that at least some of the "emeralds" worn by Cleopatra were actually peridot. Much of its recent popularity can be explained by its currently being recognized as the birthstone for the month of August, people wear the stone because it is supposed to bring the wearer success, peace, and good luck.

The United States was for many years the largest producer of peridot, the value of production in 1993 was estimated to be about $1.5 million, according to the USBM. The United States is getting major Competition from China and Pakistan for the title of world's largest producer.

he production of gem-quality sapphires in the United States is not new or recent. In 1865, the first U.S. sapphires were found in the gravels of the Missouri River in Lewis and Clark County, Montana. This was followed by subsequent discoveries on Dry Cottonwood Creek in Deer Lodge County in 1889, on Rock Creek in Granite County in 1892, and in Yogo Gulch in Judith Basin County in 1895. Additionally, small amounts of sapphire are recovered from Quartz Gulch in Granite County, Pole Creek in Madison County, the Missouri River in Chouteau County, and Brown's Gulch in Silver Bow County

Furthermore, corundum crystals, from which star sapphires have been cut, are found in Beaverhead and Madison Counties. Also, in 1895, the first sapphires were produced from the Cowee Valley in Macon County, North Carolina. But until very recently, with the exception of Yogo Gulch material, the commercial gemstone industry has had limited interest in U.S. sapphires.

Tourmaline is a complex crystalline silicate containing aluminum, boron, and other elements, used in electronic instrumentation and, especially in its green, clear, and blue varieties, as a gemstone.

Opal is brittle, heat sensitive, and breaks and scratches easily; additionally, some varieties self- destruct through the loss of water. Even with these drawbacks, opal's unsurpassed beauty guarantees its status as a premier gemstone. The derivation of its name even adds to its position. Reportedly, opal's name evolved from the Roman word opalus from the Greek word opallios meaning "to see a change of color." The Greek word was a modification of the ancient Indian Sanskrit name for opal, upala, which meant "precious stone." If one spoke in mixed tongues, then opal would be opallios upala, "to see a change of color precious stone."  

Tourmaline seems to have a special place in the hearts of mineral collectors as well as in that of gem and gemstone enthusiasts. Its nearly universal popularity is based on two very important facts: first, it is a bright and beautiful gemstone that can be found in just about any color; and second, materials that are of acceptable quality are affordable to most purchasers.

The word "rainbow" is used figuratively to describe tourmaline. In reality, it is a well recognized fact that tourmaline's diversity in color is not limited to the seven colors of the rainbow. Tourmaline can be colorless to just about any color, hue, or tone known to man. And if range of colors among different tourmalines is not enough, individual crystals can vary in color along their length or in cross-section.

Tanzanite is the blue/purple variety of the mineral zoisite which was discovered in the Meralani (Merelani) Hills of Northern Tanzania in 1967, near the city of Arusha. It is used as a gemstone. Tanzanite is noted for its remarkably strong trichroism, appearing alternately sapphire blue, violet, and burgundy depending on crystal orientation.

Tanzanite in its rough state is usually a reddish brown color. It requires artificial heat treatment to 600 °C in a gemological oven to bring out the blue violet of the stone. Tanzanite is a rare gem. It is found mostly in the foothills of Mount Kilimanjaro. The mineral is named after Tanzania, the country where it was discovered.