Garnet
Source: Brazil, India, Madagascar, Sri Lanka, Tanzania, Zimbabwe
Birthstone: January
The "Garnet" name comes from the Latin word for pomegranate, malum granatum, due to the resemblance of some varieties of garnets to red pomegranate seeds. Their use as gems has a history that goes back to the ancient Egyptians. In the ancient world, garnet was known as "carbuncle." This gem was carried by ancient travelers to protect against accidents when they were far from home.
Red garnet has a hardness of 7 to 7.5 on the Mohs scale. Varieties of Garnet include: Golden Andradite, Chrome Pyrope (red), Mozambique, Rhodolite (magenta), Spessartite (yellow/orange) and Tsavorite (green). The garnet was adopted as the New York State gem in 1969.
Chemical composition: Mg3Al2[SiO4]3
Amethyst
Source: Brazil, Uruguay, Zambia
Birthstone: February
The name "Amethyst" comes from the Greek word meaning "against drunkenness". This was perhaps due to a belief that amethyst would ward off the effects of alcohol, but most likely the Greeks were referring to the wine-like color of some varieties of the stone. Amethyst is the purple variety of the mineral quartz and is a popular gemstone. Amethyst can occur as elongated prismatic crystals which have a six sided pyramid at either end. They can also form as druzes that are crystalline crusts that only show the pointed terminations of each crystal. The color purple has long been associated with royalty, making amethyst jewelry a popular choice among royal families.
Amethyst has a hardness of 7 on the Mohs scale. Amethyst belongs to the quartz family of minerals. Quartz is one of the most commonly found minerals within the earth's crust. The chemical Silica Dioxide is the principle component in quartz as well as most other igneous rocks. Amethyst is formed from silica rich liquids deposited in gas cavities or geodes within lava.
Chemical composition: SiO2
Aquamarine
Source: Brazil, Uruguay, Zambia
Birthstone: March
The name "Aquamarine" is derived from the Latin phrase "water of the sea", named for it's greenish-blue seawater color. Aquamarine (or Aqua Beryl) develops in pegmatites and certain types of metamorphic rocks. It occurs in conjunction with quartz, microcline, muscovite pegmatites, and almandine in metamorphic rocks. Most Aquamarine comes from the pegmatites of Brazil, where crystals weighing several kilos have been found. Beryl has become an important source of the element beryllium, a metal with a variety of commercial uses, such as in the manufacturing metal alloys. Blue Spinel, a synthetic mineral, is easy and inexpensive to produce, and it is often mistakenly sold as "Synthetic Aquamarine".
Aquamarine has a hardness of 7.5 to 8 on the Mohs scale. Beryl Aquamarine is made up of beryllium aluminium silicate, sodium, lithium, and cesium.
Chemical composition: Be3Al3[SiO3]6
Diamond
Source: Africa, Australia, Canada, Russia
Birthstone: April
The name "Diamond" is derived from the name from the Greek adamas, "unconquerable", referring to its hardness. At one time over 80% of the world's rough diamonds passed through the Diamond Trading Company or DTC, which is a subsidiary of De Beers in London. In the late 1990s, Canadian prospectors discovered several abundant sources of diamonds. The Canadian Ekati Diamond Mine was opened in 1998 and produces 3 million carats of rough diamonds every year. The Diavik Diamond Mine was opened in 2004. Diamonds are categorized and valued according to the "Four C's" of diamond grading. They are cut, clarity, color, and carat. For more information on this grading system, go to: Diamond Grading - The Four "Cs".
Diamond has a hardness of 10 on the Mohs scale. Diamond is a natural allotrope of carbon. The main allotrope of carbon graphite. The crystal bond structure of diamonds give the stone its hardness and differentiates it from graphite (Diamond Chemistry). Diamond is the hardest natural occurring material. Diamonds are one of the most prized gemstones; however, diamonds have industrial applications as well. Diamond is a transparent, optically isotropic crystal with a specific gravity of 3.52, a refractive index of 2.417, and a high dispersion of 0.044. Diamonds crystallize in the cubic crystal system and consist of tetrahedrally bonded carbon atoms. The brilliance and luster of diamonds are described as adamantine, which means diamond-like. Some diamonds exhibit fluorescence of various colors under long wave ultra-violet light, but generally bluish-white, yellowish or greenish fluorescence under X-rays. Canadian diamonds, however, show no fluorescence.
Chemical composition: C
Emerald
Source: Brazil, Columbia, Pakistan, Zambia
Birthstone: May
The name "Emerald" comes from the Greek smaragdos, a name that was given to several stones having little in common except their greenish color. An emerald's color is due to small amounts of chromium and vanadium. Emeralds are very brittle and most contain flaws known as "inclusions". The multiphase inclusions in emeralds are like fingerprints and can reveal the geographic location of their origin. The French refer to the large number of inclusions in the stone as "jardin," or "garden," because they resemble foliage. Emerald is one of the most difficult gemstones to cut because of the many inclusions found in rough crystals. Emeralds with many inclusions should be treated with care and be protected from direct blows to the stone The extreme rarity of transparent emeralds can make them more valuable than diamonds.
The ancient world obtained emeralds from Upper Egypt, where they were mined and worked as early as 2000 BC, during the reign of Pharaoh Sesostris III. The Mughals of India, including the builder of the Taj Mahal, Shah Jahan, loved emeralds so much they inscribed them with sacred text and wore them as talismans. These sacred stones are called Mughal emeralds.
Emerald has a hardness of 7.5 to 8 on the Mohs scale. Emerald is a composition of Beryl, Berillium and Aluminum Silicate. Columbian emeralds have a particularly intense greenish color with a bluish tint which makes their color difficult to capture in digital photographic images.
Chemical composition: Al2Be3[Si6O18]
Alexandrite
Source: Brazil, Russia
Birthstone: June
The name "Alexandrite" comes from the stones' ostensible discovery on April 23, 1830, the day that young Russian Czar Alexander Nicolajevitch II (reigned 1855 to 1881) had his "comming of age" birthday. Alexandrite was discovered along the banks of the Tokovaya River in the Ural Mountains of Russia. This new gemstone discovered in the Tokovaya River's mica schists had the strange ability to change color under prevailing light. The most widely used variety of chrysoberyl is an alexandrite. Because of alexandrite's unique ability to absorb certain elements of the color spectrum, it looks green in daylight and reddish purple under artificial light. Natural alexandrite is very rare. The finest alexandrite crystals ever found came from the Tokovaya river deposit, and the greatest alexandrite specimen ever found is housed in Moscow's Fersman Mineralogical Museum. Most Alexandrite found on the market today is synthetic.
Chemical composition: BeAl2O4
Ruby
Source: Myanmar (Burma), Thailand
Birthstone: July
The name "Ruby" is Latin for red. The fiery red color of ruby was thought to be an inextinguishable flame lit from within. Rubies were celebrated in the Bible and in ancient Sanskrit writings as the most precious of all gemstones. Ruby is also known as the "stone of Kings". Some of the finest rubies in the world are mined in Myanmar. Other important sources include Kenya, Pakistan, Sri Lanka, Tanzania, Thailand and Vietnam.
Ruby has a hardness of 9 on the Mohs scale. The ruby belongs to the same mineral family as sapphire and is formed by heat and pressure in limestone rich in clay. The primary origin of ruby is metamorphic rocks and volcanic rocks or basalts, and secondarily alluvial. Ruby is made up of the mineral corundum, which is aluminum oxide or alumina. It becomes a ruby when it has a small impurity of chromic oxide which gives it the rich red color. If the corundum has other impurities which give it a blue color, it is called sapphire. These two gems also sometimes exhibit a six-pointed "star" effect from reflection off microscopic, needle-shaped rutile crystals which intersect at 60° angles.
Chemical composition: BeAl2O3
Peridot
Source: Burma, Pakistan, Sri Lanka, USA (Arizona)
Birthstone: August
The name "Peridot," or "Chrysolite" (golden yellow peridot), means "golden stone" in Greek. Peridot was treasured by the Egyptian Pharos. Some of Cleopatra's emeralds were actually peridots. In the Middle Ages, people wore peridot to gain foresight and divine inspiration as well as to protect them against evil. Peridot mining dates back some 4,000 years. The Peridot mineral deposits on Saint Johns Island in the Red Sea were mentioned by the greek historian Pliny in his Natural History (AD 70). The Saint Johns Island deposit still produces peridot, although most modern Peridot comes from Arizona.
Peridot has a hardness of 6 1/2 to 7 on the Mohs scale. Peridot, also called precious olivine, is a transparent green olivine. Gem-quality olivine is a mineral that composes a lot of the earth's mantel, the layer below the outer crust. It is also common in basalts on the moon. Peridot is a gemstone variety of forsterite, the magnesium-rich end of the olivine series. Chrysolite is a golden yellow variety of peridot.
Chemical composition: [Mg,Fe]2SiO4
Sapphire
Source: Australia, Brazil, Sri Lanka, Thailand, USA (Montana)
Birthstone: September
The name "Sapphire" is originally derived from Greek (sappheiros), the Sanskrit word sanipruja ("dear to Saturn"), and the Hebrew word sappir, meaning gem. The biblical Sapphira was a woman who was executed by God for lying. The oldest Sapphire mines are situated in Ceylon, or Sri Lanka, where these gemstones were mined in ancient times. The most valuable color for blue sapphire is not the darkest blue as is often claimed, but a rich yet very translucent color blue, which even in dim artificial light still appears blue. The stone cutter must align the orientation of the stone in such a way as to bring out the best possible display of color and clarity
Sapphires (Corundum) have a hardness of 9 on the Mohs scale. The blue color of sapphire is due to charge transfer involving Fe-Ti. The primary origin of sapphire is alluvial. Both Sapphires and rubies exhibit double refraction, which resolves a beam of incident light into two beams which emerge with different colors. These two gems also sometimes exhibit a six-pointed "star" effect from reflection off microscopic, needle-shaped rutile crystals which intersect at 60° angles. When these stones are cut in half-dome shape, they display this star-shaped light pattern giving them the name "Star Sapphire".
Chemical composition: BeAl2O3
Pink Tourmaline
Source: Brazil, Africa, Sri Lanka, USA (California, Maine)
Birthstone: October
The name "Tourmaline" is derived from the Sinhalese (Sri Lanka) word tura mali, meaning "stone of mixed colors." Tourmaline appears in many colors, including clear, pink, yellow, blue, red, green and black. Ancient Egyptian legend explained the array of colors in tourmaline this way: On it's long journey from the middle of the earth up toward the sun, the tourmaline traveled along a rainbow collecting all the colors of the rainbow. This is why tourmaline came to be known as "the rainbow gemstone." Each color of tourmaline is given its own name. These include rubellite (pink to red), achroite (colorless), indicolite (blue), dravite (brown), schorl (black).
Tourmaline has a hardness of 7 to 7 1/2 on the Mohs scale. Tourmaline is a complex crystalline silicate containing aluminum, boron and other elements. Tourmaline is piezoelectric which means that heating, rubbing or pressurizing the crystal gives it an electric charge It also is pleochroic, which makes it appear darker from some angles than from others.
Chemical composition: Na(Mg,Fe,Mn,Li,Al)3Al6(BO3)Si6O18(OH,F)4
Citrine
Source: Brazil, India, Madagascar, Sri Lanka
Birthstone: November
The name "Citrine" comes from the French word "citron," or "lemon," for its color. Citrine closely resembles topaz (also a birthstone for November), but is slightly softer, and has less brilliance. Citrine has been used in Greece since the Hellenistic period at the end of the 4th to the end of the 1st century BC. Citrine can permanently change color if left in direct sunlight for several hours. In ancient times, citrine was carried as a protection against snake venom. It is also thought to aid digestion, and remove toxins from the body.
Citrine has a hardness of 7 to 7 1/2 on the Mohs scale. Citrine is a coarse-grained, transparent variety of the silica mineral quartz. The yellow color is derived from the presence of iron. The darker the color of the citrine, the higher the grade. Purple amethyst will turn to citrine when heated in a kiln for a certain period of time.
Chemical composition: SiO2
Tanzanite
Source: Tanzania, Kenya
Birthstone: December
The name "Tanzanite" was coined by Tiffany & Co. after the principle place where the stone is found: Tanzania. Tanzanite is a newly discovered gemstone. In July 1967, a tailor named Manuel d'Souza was prospecting for rubies in Tanzania Africa when a group of Masai tribesmen led him to a deposit of blue stones. Masai legend is that cattle herders first noticed this stone some 30 years previously, after a fire caused by lightning burned large areas in Tanzania. The herders noticed that brown zoisite crystals had turned a deep blue-purple due to the heat from the fire. The entire area soon became covered in mines, and d'Souza was unable to maintain control over his mining claim. In 1971, the Tanzanian government took control of the mines and turned them over to the State Mining Corporation in 1976.
Tanzanite has a hardness of 6 to 6 1/2 on the Mohs scale. Most of the tanzanites on the market has been heat-treated to 620°C (932°F) to produce the deeper blue color. The stone has a very pronounced pleochroism which reflects different colors from different angles. Chrome tanzanite (chrome zoisite) obtains its vivid green color from chromium content.
Chemical composition: CaA13(O/OH/SiO4)Si207
The Tradition Of Birthstones
The tradition of birthstones came from the use of decorative stones in the Breastplate of Aaron as described in the Bible (Exodus 28, 15-30). The breastplate was a ceremonial religious garment set with twelve gemstones that represented the twelve tribes of Israel and corresponded with the twelve signs of the zodiac and hence, the twelve months of the year.
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