Birthstones

What is a birthstone?

Birthstone is a gem associated with a month of the year. According to tradition, a birthstone brings good luck to a person born in its month. Each birthstone also corresponds to a sign of the zodiac. However, the birth dates for each sign do not match the beginning and end of each month.



Garnet-January

 January- Garnet

Garnet is any of a group of hard, glassy minerals. This group of silicate minerals includes six major types: almandine, andradite, grossularite, pyrope, spessartite, and uvarovite. Garnets are composed of silica and such elements as aluminum, calcium, iron, magnesium, and manganese. They range in color from red, brown, and black to various shades of yellow and green. Crystals of garnet are found in all types of rock, but chiefly in metamorphic varieties.

Some garnet crystals are used in making jewelry. Red garnet, a gem-quality garnet, commonly includes a mixture of almandine and pyrope. Garnets are also used as abrasives for grinding and polishing. Garnets are found throughout the world. Those of gem quality are mined chiefly in central Europe, Russia, and South Africa.

Amethyst-February

February-Amethyst

Amethyst is a purple or bluish-violet gem. It is used to make rings, necklaces, and brooches. The amethyst is a variety of quartz. The color of the amethyst is believed to be caused by impurities such as iron and manganese. Amethysts have been mined in Brazil, Uruguay, Siberia, India, Sri Lanka, Madagascar, Mexico, and Canada. The amethyst is the birthstone for February. The Oriental amethyst is a purple variety of the mineral corundum.



Aquamarine-March

March- Aquamarine          

Aquamarine is a light blue or bluish-green variety of a gemstone called beryl. The most popular color is a clear sky-blue. Aquamarines are often treated with heat or radiation to improve their color. Almost all aquamarines are transparent. These stones are cut in facets (polished flat surfaces) and used in all types of jewelry. The aquamarine and the bloodstone are the two birthstones for March.

Aquamarines have been known since ancient times. The ancient Romans believed the gem could cure laziness and produce courage. The most important source of aquamarines is Brazil. The gem is also found in Argentina, China, India, Madagascar, Myanmar, Namibia, Northern Ireland, Norway, Russia, and the United States.

April- Diamond

Diamond-April

Diamond is the hardest naturally occurring substance, and also one of the most valuable natural substances. Because of its hardness, the diamond is the most lasting of all gemstones. In Europe, North America, and Japan, diamonds are widely used for engagement and wedding rings. Diamonds are also used in industry for cutting, grinding, and boring other hard materials. About half of the world's natural diamonds are suitable only for industrial use. A small percentage is set in jewelry. Diamond is the birthstone for April.

Diamonds are crystals that are made up almost entirely of carbon. Some diamond crystals have six faces, but most form octahedrons, which have eight faces (see Octahedron). Other crystal shapes also occur, some of which are complex. Natural diamonds probably form in Earth's upper mantle—the zone beneath the crust—where high temperature and pressure cause diamonds to crystallize. Diamonds are later brought to Earth's surface by volcanic activity.

A diamond can only be cut by another diamond. However, a diamond can be cleanly broken with a sharp, accurate blow because of its cleavage. Cleavage is a property some minerals have of splitting in certain directions and producing flat surfaces. A diamond will not dissolve in acid. But it can be destroyed when it is subjected to intense heat. If a diamond is heated in the presence of oxygen, it will burn and form carbon dioxide. If it is heated without oxygen, a diamond will turn to graphite, a form of carbon so soft that it is used as a lubricant.

Emerald-May

May- Emerald

Emerald is a rich green gemstone that is a variety of the mineral beryl. It owes its color to minute amounts of chromium in the crystals. Pure beryl is beryllium aluminum silicate. The value of an emerald lies in its color and its freedom from flaws and inclusions (other substances enclosed in the crystals). An emerald with a blue tint is more valuable than one with a yellow tint. Most emerald crystals contain minute fractures, which are sometimes called veils, and various kinds of inclusions. Perfect emeralds are very rare and therefore may be more expensive than diamonds. Emeralds are harder than quartz, but not as hard as sapphire.

The finest emeralds are obtained from Colombia. Afghanistan, Brazil, India, Madagascar, Pakistan, Russia, Zambia, and Zimbabwe also produce emeralds. In the United States, North Carolina has produced some emeralds. Emeralds may be produced synthetically. The emerald is the birthstone for May.

June- Pearl

Pearl- June

Pearl is one of the most valuable gems. Large, perfectly shaped pearls rank in value with the most precious stones. But pearls are different from other gems. Most gems are minerals that are mined from beneath the earth. But pearls are formed inside the shells of oysters. Mineral gems are hard and usually reflect light. However, pearls are rather soft, and they absorb, as well as reflect, light.

Oysters and other shell-forming mollusks make a special substance, called nacre that lines the insides of their shells. This smooth lining is called the nacreous layer, or pearly layer, and it is often lustrous. It is formed by cells from a fleshy body organ called the mantle. When a foreign substance, such as a bit of shell or a tiny parasite, enters the body of the mollusk, the mantle cells begin to work. They cover the invading substance with thin sheets of nacre. They build successive circular layers of nacre until the foreign body is enclosed in the shell-like substance, forming the pearl.

The pearl has the same luster and color as the lining of the shell of the mollusk. But few pearl-forming mollusks produce the beautifully colored nacre that is essential for valuable pearls. Valuable pearls come from some species of oysters and other mollusks that live in tropical seas. Some species of mussels found in rivers also produce precious pearls. Edible clams and oysters have dull shells, so their pearls are without luster. As a result, they have no value as gems.

Ruby-July

July- Ruby

Ruby is the red gem variety of the mineral corundum. Varieties of corundum are called sapphires if they are any color other than red. Chemically, a ruby is an aluminum oxide.

Rubies get their color from traces of chromium in the aluminum oxide. The red of most rubies has a brownish or yellowish tint. The rarest, most highly prized rubies are pure red.

Rubies and sapphires are second only to diamonds in hardness, and fine-quality rubies are among the costliest of all gems. The finest rubies come from Myanmar. Other primary producers of rubies are Kenya, Tanzania, and Madagascar.

A star ruby cabochon shows a six-rayed star within it when seen in a bright light. A cabochon is a rounded, polished stone.

Millions of carats of inexpensive synthetic rubies are made each year. But a demand for real gems has allowed the natural stones to maintain their high value. It can be hard to distinguish between natural and synthetic rubies, even for experts. Experts are also challenged when determining whether the color of a natural ruby has been improved by heating. Ruby is the birthstone for July.

August- Peridot



Peridot-August

Peridot is a transparent gem that is almost always some shade of green because of its iron content. Peridots are a variety of a common rock-forming mineral called olivine. Jewelers cut and polish the highest-quality Peridot stones so that each gem has many flat surfaces called facets. Faceted peridots are used in all types of fine jewelry. Jewelers cut lesser-quality peridots into a rounded style called cabochon, or polish them with abrasives in a process called tumbling. These lesser-quality peridots are used in costume jewelry and decorative objects. Peridot is one of the two birthstones for August.

Peridots have been known since Biblical times. The earliest source of peridots was Jazirat Zabarjad (St. John's Island), off the Egyptian coast in the Red Sea. In the United States, Arizona and New Mexico are important commercial sources of Peridots.



Sapphire-September

September- Sapphire

Sapphire, a hard and clear gem, is a variety of the mineral corundum. The best-known sapphires are blue. Their color results from small amounts of iron and titanium in the stone. Sapphires are also found in many other colors, including yellow, green, white, black, violet, and orange. The red variety of corundum is known as a ruby.

The most valuable sapphires once came from Kashmir, in India. They are a magnificent cornflower blue, the color to which all sapphires are compared. Today, Thailand is the most important source of blue sapphires. Blue and fancy sapphires are also found in Myanmar, Sri Lanka, Australia, and the state of Montana in the United States.

Among minerals, sapphires and rubies rank second only to diamonds in hardness. For this reason, sapphires are sometimes used as abrasive or polishing agents. Large numbers of inexpensive imitation sapphires are manufactured every year. But the natural stones have maintained their high value because of a demand for the real gems. Gemologists (gem experts) can distinguish between imitation and natural sapphires. Sapphire is the birthstone for September.

October- Opal

Opal is a gemstone that contains a rainbow of colors. Opals consist of silica and water. Silica, a compound of silicon and oxygen, is the main ingredient in sand. The background colors of an opal may be black, blue, brown, gray, or white. Opals show brilliant colors when turned in a bright light.

Opal-October

Opals are unique among gemstones because of their unusual internal structure. This structure consists of numerous tiny spheres of silica that are packed together in a regular pattern to form layers. The refraction (bending) of light between these layers causes the light to break up into the colors of the rainbow, thus producing the gemstone's extraordinary flashes of color. Opals may be found in irregular patches, often filling cavities and cracks in rocks.

In some opals, the water dries up and the opal becomes covered with tiny cracks. This process is called crazing, and it detracts from the value of the stone. Opals also are not as hard as most gems, and they may easily be scratched or chipped. The opal is one of the birthstones for October.



Citrine-November

November- Topaz

Topaz is a white or light-colored mineral sometimes cut into gems. It is a compound of aluminum, fluorine, silicon, oxygen, and hydrogen. Its chemical formula is Al2 (SiO4) (OH, F) 2. Trace impurities give topaz crystals a wide variety of colors. Topaz is hard. It defines an 8 on the Mohs hardness scale, a ranking of mineral hardness commonly used by geologists. Small amounts of topaz occur in some igneous rocks, rocks that form when molten rock cools and solidifies, and metamorphic rocks, rocks that have been changed by heat and pressure.

Blue Topaz- November

Jewelers cut transparent topaz crystals into gems. The most desirable topaz gems range in color from completely colorless to gold, orange, blue, and pink. Exposing some topaz crystals to heat or radiation can dramatically enhance or even change their color. Jewelers sell blue topaz as a substitute for the gem aquamarine. Citrine, a yellow or brownish variety of quartz, is sometimes sold as a substitute for topaz.

Topaz is found in many parts of the world. Brazil produces most of the world's gem-quality topaz. Many museum collections have large, beautiful topaz crystals that weigh hundreds of pounds or kilograms.



Turquoise-December

December- Turquoise

Turquoise is a mineral widely used as a gemstone. It is prized for its color, which ranges from sky-blue to blue-green or yellow-green. Turquoise is relatively soft, and so it is easy to shape and polish. It has a dull, waxy luster and is nearly opaque (nontransparent). Turquoise consists chiefly of a hydrous aluminum phosphate, a compound in which aluminum and phosphorus are chemically combined with water. It also contains copper, which gives it its bluish color.

Turquoise occurs in arid regions. It is formed when surface rocks that are rich in aluminum undergo a chemical change. In most cases, turquoise results from the weathering of lava. Major deposits of turquoise are found in Iran and Tibet. Large amounts of the mineral also occur in the Southwestern United States, especially in Nevada and New Mexico.

People have used turquoise for jewelry and other decorative purposes since ancient times. It is one of the December birthstones. The demand for turquoise remains so great that artificial varieties of the stone are produced.