January • February • March • April • May • June • July • August • September • October • November • December
January
The Birthstone for the Month of January is Garnet. They are the Zodiac birthstones for Aquarius, and an alternate for Capricorn. Garnets are given on the 2nd and 6th anniversary. Garnets are associated with strength, prosperity, and health.
As a gemstone, garnets have had a mixed reputation. Garnets do possess high indices of refraction, are hard enough, have pretty colors, are wonderfully transparent, lack cleavage and are durable; thus making good candidates for gemstones. However, many people consider garnets to be inferior to other colored gems. This may be due to garnet’s relative abundance and widespread use, and therefore a (typically) low price. Garnets are greatly variable in colors and varieties, though, and many of these are both rare and beautiful, producing genuinely precious gemstones. Some garnets are truly unique in the mineral kingdom and have much to offer as both gemstones and mineral specimens.
The main differences in physical properties among the members of the garnet group are slight variations in color, density, and index of refraction. The most common crystal shape for garnet is the rhombic dodecahedron, a twelve sided crystal with diamond-shaped (rhombic) faces. This basic shape is the trademark of garnets, for no other crystal shape is so closely associated with a single mineral group like the rhombic dodecahedron is with garnets. Most garnets are red in color, leading to the erroneous belief that all garnets are red. In fact a few varieties, such as grossular, can have a wide range of colors, and uvarovite is always a bright green. As a mineral specimen, garnets usually have well shaped and complex crystals and their color and luster can make for a very beautiful addition to a collection. At times garnets are accessory minerals to other valuable and pretty gem minerals such as topaz, beryl, tourmaline, vesuvianite and diopside making these specimens extra special.
Rose quartz is one of the most desirable varieties of quartz. The pink to rose red color is completely unique, unlike any other pink mineral species. The color is caused by iron and titanium impurities. Rose quartz is used as an ornamental stone and as a gemstone. It is also an alternate birthstone for the month of January. Rose quartz is associated with emotional balance and forgiveness. Although rose quartz is usually too cloudy to be used as a cut gemstone, a few exceptional pieces are found with enough clarity and color to make fine gems. Most gemmy rose quartz is used as cabochons where the clarity is not as important as the color. Rose quartz is also a very attractive ornamental stone and is carved into spheres, pyramids, obelisks, figurines and ornate statues.
Rose quartz is found in Madagascar, India, Germany, and several localities in the USA. Much rose quartz was extracted from a famous site near Custer, South Dakota, but now, most of the world’s supply of good quality rose quartz comes from Brazil. Brazil is also the only current source of true well-formed crystals of rose quartz. Rose quartz was once believed to be only massive, found primarily in the cores of pegmatites. This lack of crystals is somewhat of a curiosity because quartz crystallizes into well-formed crystals in all its other macroscopic varieties. So amazing are the rose quartz crystals that the first ones discovered were dismissed as fakes by mineralogists from around the world. If rutile needles are present in the rose quartz then a star effect or asterism is sometimes seen. The star is best seen when light is viewed through the rose quartz. This is different from asterisms in most other gemstones, such as ruby and sapphire, where the stars are seen when light is shown on the gems.
February
The Birthstone for the Month of February is Amethyst. It is also the Zodiac stone for the constellation of Pisces. Amethyst is associated with spirituality, wisdom, sobriety, and security.
Amethyst is the purple variety of the mineral quartz and is a popular gemstone. Although it must always be purple to be amethyst, it can and does have a wide range of purple shades. Its color is unparalleled, and even other, more expensive purple gemstones are often compared to its color and beauty. If it were not for its widespread availability, amethyst would be very expensive. The name “amethyst” comes from the Greek and means “not drunken.” 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 almost wine-like color of some stones that they may have encountered.
Amethyst can occur as long prismatic crystals that have a six sided pyramid at either end or can form as druzes that are crystalline crusts that only show the pointed terminations. As a mineral specimen, amethyst is popular for its color and nice crystal shapes that produce a handsome, purple, sparkling cluster. However, amethyst is not the same everywhere. Different localities can produce a unique amethyst to that particular region or even to that particular mine. Experts can often identify the source mine that a particular amethyst came from. The key to this is the specimen’s color, shape of crystal, inclusions, associations and character of formation.
Often, cut gems of amethyst are graded using the terms: Siberian, Uruguayan or Bahain to represent high medium and low grade respectively, regardless of the actual source. Because of the patchiness of the color distribution in the crystals, Amethyst is often cut as brilliant round cuts to maximize the color. Other cuts can be used when the color is better distributed. The color purple is traditionally the color of royalty and amethyst has been used since the dawn of history to adorn the rich and powerful monarchs and rulers. Today, amethyst is a lovely and affordable gemstone that is fortunately available in a wide variety of cut and uncut stones that we can all possess and admire.
Prasiolite is the leek-green variety of quartz, rare in nature but used as a gemstone, sometimes (wrongly) called Green Amethyst. Onyx is a black or white variety of chalcedony (cryptocrystalline quartz), usually with alternating bands. It is fine-grained quartz whose crystals are too small to see. Onyx is popular as a carving stone, since clever use of alternating bands of black and white can create a highly appealing carving. Onyx is the traditional birthstone for February. It is associated with relaxation and comfort.
March
The Birthstone for the Month of March is aquamarine which is blue, or perhaps more correctly, blue-green or aqua variety of the mineral beryl. Aquamarine is the birthstone for March, and it is commonly recognized as the Zodiac stone for the constellation of Scorpio (although it is usually referred to as beryl in this regard). As beryl, aquamarine is mentioned in the Bible. Aquamarine jewelry is associated with beauty, honesty, loyalty, and happiness.
Other gemstone color varieties that are also the mineral beryl include emerald, morganite, and heliodor. The hardness and durability of aquamarine make it a fine gemstone, and its light blue or aqua color makes it a fine choice when the harsher colors of some other gemstones would overwhelm or distract from an outfit. It’s typical delicate color allows it to be used in a larger stone where its beauty can be impressive. Aquamarine is colored by trace amounts of iron, and most gem aquamarines have been heat treated to produce the popular blue-green colors from less desirable yellow or pale stones. The leading producer of aquamarines is the country of Brazil, which has many mines. Pakistan, as well as many U.S. localities, produces wonderful specimens as well. Recently, a new mine in China has produced large numbers of excellent flat (stubby) hexagonal crystals, for a fraction of the price of those beautiful Pakistan specimens.
Aquamarine is sometimes found in huge crystals (unlike emerald). It is also known in a glassy form, often without showing crystal form, and sometimes with many holes or other odd shapes. Other times a large cluster of prismatic crystals can be seen to all have the same alignment – a sign that it is really a single crystal with many faces.
Bloodstone is a green variety of chalcedony (cryptocrystalline quartz), containing red speckles. It is impure fine-grained quartz whose crystals are too small to see. The red speckles in the green stone remind some people of drops of blood, leading to a Christian use where bloodstone represents the blood of Jesus. The stone has been used to carve scenes including the crucifixion, from whence came the alternate name, “the martyr’s stone”. A second alternate name,heliotrope, refers to the way some polished specimens reflect sunlight. Bloodstone is the traditional birthstone for March, the Zodiac birthstone for Aries, and an alternate for both Aquarius and Pisces. It is associated with endurance.
April
The Birthstone for the Month of April is the Diamond, the ultimate gemstone, having few weaknesses and many strengths. It is well known that Diamond is the hardest substance found in nature, but few people realize that Diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). But even as hard as it is, it is not impervious. Diamond has four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it will cleave, or split. A skilled diamond setter and/or jeweler will prevent any of these directions from being in a position to be struck while mounted in a jewelry piece.
As a gemstone, Diamond’s single flaw (perfect cleavage) is far outdistanced by the sum of its positive qualities. It has a broad color range, high refraction, high dispersion or fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability. Diamond is the April Birthstone and an alternate Zodiac stone for the Constellation of Aries. Diamonds may be nearly any color in the rainbow plus browns, grays, and white. Shades of yellow are most common, followed by colorless. Blue, black, reddish, and greenish are more valuable (some extremely so).
Diamonds are found in a type of rock called “Kimberlite”, which comprises the core of certain volcanoes over especially thick portions of the earth’s crust. This hard stone is mined and then crushed between giant steel rollers. The kimberlite is reduced to fine gravel, yet the extremely hard diamonds come out unharmed! Water is added and a grease covered roller sorts the diamonds from the gravel, as the diamonds stick to the grease. Typically, a single carat of diamond is recovered from a ton of rich ore.
Diamonds are found in many areas including South Africa, Russia, and even in Arkansas in the USA. In all cases, the diamonds formed deep within the earth’s mantle, and were brought to the surface in volcanic eruptions. In many cases, the diamonds weathered out of the kimberlite by natural processes, and were transported downstream by water. Many diamonds are mined in the resulting alluvial deposits in areas such as along the coast of South Africa.
May
The Birthstone for the Month of May is Emerald, the green variety of the mineral Beryl. Emerald is both the May birthstone and the Zodiac stone for the constellation of Cancer. Emerald gemstones are associated with patience, understanding, and foresight. The wonderful green color of emerald is unparalleled in the gem kingdom. Emerald’s precious green color is caused by small amounts of chromium and enhanced by traces of iron. Unlike other beryls, emeralds usually contain inclusions and other flaws. These flaws are not looked on as negative aspects for emerald like they would be for other gemstones. Indeed, these flaws are considered part of the character of the stone and are used to assure the purchaser of a natural stone. Even artificial emeralds often contain flaws, however, as the process of growing artificial emeralds mimics the way nature does it (slow crystal growth from a molten mix).Nearly all emeralds, even many “natural” stones, have been treated to improve clarity, generally by immersing them in oil. For gemstones, green colored oil is sometimes used, “improving” the color as well. Unfortunately, this oil may evaporate over the years, making flaws appear where none were visible at the time of purchase. A high-grade mineral oil may be used to improve the appearance again.
Chrysoprase is a green variety of chalcedony (cryptocrystalline quartz). It is usually an apple-green, but can vary to a dark green. If the specimen contained flecks of red, it would be called.Bloodstone.Chrysoprase (sometimes called simply “prase”, especially for darker specimens) is fine-grained quartz whose crystals are too small to see. The color is due to the presence of nickel.Chrysoprase is the traditional birthstone for May, and is associated with the values of fertility and secrecy.
June
The Birthstone for the Month of June is Alexandrite, the color changing variety of the mineral Chrysoberyl. Alexandrite’s color varies from red to green depending upon the light source. It is an alternate (modern) Zodiac stone for the constellation of Gemini. Alexandrite is associated with balance, confidence, and joy.
Alexandrite is named for the former czar of Russia, Alexander II, and was first discovered in the Ural Mountains of Russia, supposedly on the day of his birth. Chromium gives alexandrite its color and while, in most minerals, a trace element like chromium would provide only one color to the mineral, in alexandrite it gives it two! Coloring agents are dependent on the wavelength of light and the chemical bonds in the crystal to determine the color that they will cause. An element like copper, in normal light, can cause a green color in malachite and a blue color in azurite; it all depends on the character of the chemical bonding. In a single specimen of alexandrite, the chromium is in such a balanced situation that the color of the specimen depends on the character of light that hits the crystal. If the light is natural sunlight or fluorescent light, the crystal will be green; however, if the light is incandescent light from a common indoor light bulb, then the crystal will appear red.
Synthetic corundums spiked with trace elements that yield an alexandrite-like color change are sold as alexandrite on the gemstone market. These stones have a red-violet, near-amethyst color in incandescent light and a blue-violet color in daylight. They are far less expensive than natural Alexandrite, which are some of the rarest and most expensive of gemstones.
Oligoclase is not a well known mineral but has been used as a semi-precious stone under the names of sunstone and moonstone. Sunstone has flashes of reddish color caused by inclusions of hematite. Moonstone shows a glowing shimmer similar to labradorescence, but lacking in color. The display is produced from lamellar intergrowths inside the crystal. These intergrowths result from compatible chemistries at high temperatures becoming incompatible at lower temperatures and thus a separating and layering of these two phases. The resulting shimmer effect is caused by a ray of light entering a layer and being refracted back and forth by deeper layers before it exits the crystal. This refracted ray has a different character than when it went in and produces the moonlike glow. Moonstone is an alternate birthstone for the month of June.
Oligoclase is a member of the Plagioclase Feldspar Group. The plagioclase series comprises minerals that range in chemical composition from pure NaAlSi3O8, Albite to pure CaAl2 Si2 O8, anorthite. Oligoclase by definition must contain 90-70% sodium to 10-30% calcium in the sodium/calcium position of the crystal structure. The various plagioclase feldspars are identified from each other by gradations in index of refraction and density in the absence of chemical analysis and/or optical measurements. All plagioclase feldspars show a type of twinning that is named after albite. Albite Law twinning produces stacks of twin layers that are typically only fractions of millimeters to several millimeters thick. These twinned layers can be seen as striation like grooves on the surface of the crystal and unlike true striations these also appear on the cleavage surfaces. The Carlsbad Law twin produces what appear to be two intergrown crystals growing in opposite directions. Two different twin laws, the Manebach and Baveno laws, produce crystals with one prominant mirror plane and penetrant angles or notches into the crystal. Although twinned crystals are common, single crystals showing a perfect twin are rare and are often collected by twin fanciers.
July
The Birthstone for the Month of July is the Ruby. The gemstone Ruby is the red variety of the mineral Corundum, the second hardest natural mineral known to mankind. Ruby is the July birthstone, and the Capricorn Zodiac stone. Ruby has been associated with the values of love, success, integrity, passion, and promise. All colors of corundum other than red or white are called Sapphire the red color in ruby is caused by trace amounts of the element chromium. The best shade of red for ruby is often given the name “pigeon blood red”, but ruby can be any shade of red up to almost pink.
Oriented rutile crystal inclusions cause a six-rayed-star light effect (called asterism) to form the popular Star Ruby.Rubies come from all over the world but good gemstones are found at Thailand, India, Madagascar, Zimbabwe, North Carolina in the U.S., Afghanistan, Pakistan, Sri Lanka, Kenya, Tanzania, Kampuchea, and perhaps most notably, Burma. Like most gemstones from the antiquities, Ruby is one of the Biblestones. In Exodus, the Breastplate of Aaron is described as containing a “sardius”, the ancient name for ruby.Rubies have a famous place in science – the first lasers were made from artificial ruby crystals. They still are used for this purpose although other materials offer improved efficiency. Some natural ruby crystals show the fluorescence (actually very short term phosphorescence) that makes a laser possible.
August
The Birthstone for the Month of August is the Peridot. Peridot (pronounced pair-a-doe) is the gem variety of olivine. Peridot is the birthstone for August and the Zodiac stone for the constellation Libra (astrological sources refer to Peridot as Chrysolite). Peridot is associated with the values of fame, dignity, protection, and success.
Olivine, which is actually not an official mineral, is composed of two minerals: fayalite and forsterite. Fayalite is the iron rich member and forsterite is the magnesium rich member. Olivine’s formula is written as (Mg, Fe) 2SiO4 to show the substitution of the magnesium and iron. Peridot is usually closer to forsterite than fayalite in composition although iron is the coloring agent for Peridot. The best colored Peridot has an iron percentage of less than 15% and includes nickel and chromium as trace elements that may also contribute to the best Peridot color.
Gem quality Peridot comes from the ancient source of Zagbargad (Zebirget) Island in the Red Sea off the coast of Egypt, Mogok, Myanmar (formerly known as Burma), Kohistan, Pakistan, Minas Gerais, Brazil, Eifel, German, Chihuahua, Mexico, Ethiopia, Australia, Peridot Mesa, San Carlos Apache Reservation, Gila County, Arizona and Salt Lake Crater, Oahu, Hawaii, USA. The best quality Peridot has historically come either from Myanmar or Egypt, but new sources in Pakistan are challenging that claim with some exceptional specimens. The Arizona gem material is of lesser quality, but is far more abundant and is therefore much more affordable. An estimated 80 – 95% of all world production of Peridot comes from Arizona. The Myanmar, Pakistani and Egyptian gems are more rare and of better quality; thus quite valuable approaching the per carat values of top gemstones. Possibly the most unusual Peridot is that which comes from iron-nickel meteorites called pallasites, some of which are actually facetted and set in jewelry.
Peridot is perhaps derived from the French word Peridot which means unclear, probably due to the inclusions and cloudy nature of large stones. It could also be named from the Arabic word faridat which means gem. In either case, Peridot has been mined as a gemstone for an estimated four thousand years or better, and is mentioned in the Bible under the Hebrew name of pitdah (see Biblestones). Peridot gems along with other gems were most likely used in the fabled Breastplates of the Jewish High Priest, artifacts that have never been found. The Greeks and Romans referred to Peridot as topazion and topazius respectively and this name was later given to topaz, to end the confusion with the two gems. Historical legend has it that Peridot was the favorite gemstone of Cleopatra. Pliny wrote about the green stone from Zagbargad Island in 1500 B.C. Even until recently jewelers have used the term “chrysolite” (latin for golden stone) in referring to Peridot gems for some reason. This term has also been used to refer to other gemstones, of a more golden color.
Zagbargad (Zebirget) Island has been known as St John’s Island and was mined for centuries. Before World War I, this island was extensively mined and produced millions of dollars worth of gems. Since then the mining has been off and on and at present is all but nonexistent. Still, specimens from here are available at times and it certainly is a classic mineral locality.
Throughout time, Peridot has been confused with many other gemstones, even emerald. Many “emeralds” of royal treasures have turned out to be Peridot! Although Peridot is distinctly a different shade of green, many jewelers refer to Peridot as “evening emerald”. Emerald is a dark green as opposed to a yellow green and always contains inclusions. Other green gemstones confused with Peridot include apatite (which is much softer); green garnets (have no double refraction), green tourmaline and green sinhalite (both of which are strongly pleochroic), moldavites (no double refraction) and green zircon (significantly heavier). All of these gemstones rarely have as nice a yellow component to their green color as does most Peridot, but darker green Peridot can be confusing when good crystal form is not discernible.
Peridot is a beautiful gemstone in its own right and is widely popular. Its popularity is said to be increasing yearly and with new finds in Pakistan producing exceptionally well crystallized specimens, Peridot can be fun to collect for years to come. Olivine has the same overall composition as the Earth’s mantle, and thus can be considered to be the most common mineral INSIDE the Earth (the 1600 mile wide solid iron core is second). In a sense then, Peridot may be by far the most common gemstone. Some volcanoes, including those located in Hawaii, occasionally produce sands which are composed of transparent green grains of Peridot. On the Big Island, the sands mostly appear black except on a beach near the southernmost tip of the island.
September
The Birthstone for the Month of September is the Sapphire. The Sapphire is chemically and structurally the same as a Ruby, both are varieties of the mineral corundum. Sapphires are well known amongst the general public as being blue, but can be nearly any color except shades of red or pink (since those are called rubies). Sapphire is also the Zodiac stone for the constellation of Taurus the Bull. It is associated with the values of truth, sincerity, commitment, and loyalty.
The blue color is by far the most admired color for sapphire but orange-pink, golden, white, and even black have generated much interest in the gem trade. Tennis bracelets are available that contain a complete rainbow of sapphire gemstones. Oriented rutile crystal inclusions cause a six-pointed-star light effect (called asterism) to form the popular Star Sapphire. Sapphires are well known from such places as Sri Lanka and India, and excellent specimens are also found in Tanzania and the Kola Pennensula of Russia. In addition, sapphires are found in many places throughout the world, including North Carolina, Brazil, and China. Sapphires are extremely durable (only diamond and moisannite are harder). Artificial sapphire crystals are used as the crystal face in genuine Rolex watches, and are extremely scratch resistant.
October
The Birthstone for the Month of October is the Opal. The Opal is an alternate Zodiac stone for Aries, Libra, and Scorpio; and the gemstone gift for the 18th anniversary. Opal has been associated with hope, faith, and confidence. Opal has been a popular gem for many centuries. It has the same chemical formula as quartz with the addition of 5 to 10 percent water. Structurally it consists of tiny spheres with water filling the gaps. The spheres in most Opals are irregular in size and inconsistent in concentration, yet in Precious Opal, the variety used most often in jewelry; there are many organized pockets of the spheres. These pockets contain spheres of approximately equal size and have a regular concentration, or structure, of the spheres. This has the effect of diffracting light at various wavelengths, creating colors. Each pocket produces a different color, with a different intensity depending on the angle from which a viewer sees it. The multicolored flashes of light that Opal emits gives it a truly beautiful and valuable look, called a play of light.
The name opal probably is derived from the Sanskrit name for precious stone; upala. It has been mined for centuries, at least since Roman times when they extracted the opal from areas now within the Czech Republic. The Aztecs made use of local Mexican sources as did the Spaniards when they exported the material back to Europe. Today most precious opal comes from Australia with significant sources from Mexico and the Western United States. Not all opal is so precious however. Common opal lacks a play of light, color or luster and is (after all) common. Opal is often imitated, forged and “enhanced”. While opal is generally white or colorless, it may also be pale yellow, pale red, gray or black when impurities are common. Diffraction can cause flashes of any color of the rainbow (opalescence). Note that the water in opal’s structure may be critical for the optimal play of color. Over time, a once beautiful opal may become dull, due to the loss of water. For this reason, opal miners store their “rough” in jars full of water. It may be wise to store valuable opal jewelry the same way!
Tourmaline is the traditional birthstone for October, and is given as the gemstone for the 8th anniversary. It is associated with balance, endurance, and safety. Most people consider tourmaline to be a single mineral. But in fact it is a group named for several different, but closely related minerals. Members of the Tourmaline Group are favorites among mineral collectors. Their rich and varied colors can captivate the eye; even the black opaque tourmalines can shine nicely and produce sharp crystal forms. Tourmalines are cut as precious gems, carved into figurines, cut as cabochons, sliced into cross-sections and natural specimens are enthusiastically added to many a rock hound’s collection.
Tourmaline can be nearly any color of the rainbow, a fact used to colorful effect in some tennis bracelets. Elbaite is the tourmaline mineral that is most often found in jewelry, as its color is extremely variable with the most common colors being red, pink, green, blue, orange and yellow. Elbaite has many variety names based on color. A beautiful blue variety is called indicolite (also known as indigolite), the pink to red variety is called rubellite, and the green variety is known as verdelite. Often a specimen can have more than one color zone in the same crystal, with the most famous variety being a pink and green combination called watermelon tourmaline.
There are many unique properties of tourmalines. First, they are piezoelectric which means that when a crystal is heated or compressed (or vibrated) a different electrical charge will form at opposite ends of the crystal (an electrical potential). Conversely if an electrical potential is applied to the crystal, it will vibrate. Secondly they are pleochroic which means that the crystal will look darker in color when viewed down the long axis of the crystal than when viewed from the side. This property goes beyond the idea that the crystal is just thicker in that direction. Even equally dimensioned crystals will demonstrate this trait. This property can be used as an advantage by gem cutters who may wish to enhance a crystal’s pale color or weaken a strongly colored crystal.
The four most common and well known tourmalines are distinguished by their color and transparencies. Elbaite is the gemstone tourmaline and comes in many varied and beautiful colors. It is transparent to translucent and is highly prized as minerals specimens and as gemstones. Elbaite is easily the most colorful of all the gemstones. The iron rich schorl is the most abundant tourmaline and is black and opaque. It is a common accessory mineral in igneous and metamorphic rocks and can form nice crystals. Although too opaque to be used as a gemstone, schorl is used as an ornamental stone when found as inclusions in quartz, a stone is called “tourmalinated quartz”. Usually when someone refers to tourmaline they are referring to either elbaite or schorl. The two other more common tourmalines; dravite and uvite are much less common than elbaite or schorl, but they are getting noticed for their beautiful specimens. Some of dravite’s crystals are nicely formed, translucent brown and they can reach a rather large size. Uvite is a green translucent to opaque tourmaline that is growing in popularity and is being cut as a gemstone.
November
The Birthstone for the Month of November is Topaz. Topaz is the Sagittarius Zodiac stone, blue topaz has been considered a valid alternate birthstone for December, and is given on the 4th anniversary. Golden topaz is given on the 23rd anniversary. Topaz is associated with the values of strength, wisdom, and courage.
Topaz is a common gemstone that has been used for centuries in jewelry. Its golden brown to yellow color is classic but is confused with the less valuable citrine, which is sometimes wrongly sold under the name topaz. The blue topaz that is often confused with aquamarine is rarely natural and is produced by irradiating and then heating clear crystals. Topaz is the hardest silicate mineral and one of the hardest minerals in nature. Topaz crystals can reach incredible size of several hundred pounds. Topaz can make very attractive mineral specimens due to their high luster, nice colors and well formed and multifaceted crystals. Topaz may be colorless, yellow, orange, red, blue and green.
Citrine is the traditional birthstone for November, and is an alternate Zodiac stone for Scorpio. Citrine jewelry is given as the gemstone gift for the 13th and 17th anniversaries. Citrine is associated with the values of hope, cheerfulness, youth, health, and fidelity. Citrine is any quartz crystal or cluster that is yellow or orange in color. Although often cut as a gemstone, citrine is actually somewhat rare in nature. Most citrines on the market have been heat treated. Specimens of low grade, inexpensive amethyst or smoky quartz are often cooked at high temperatures to produce the more profitable orange yellow citrine. Citrines whose colors have been produced by artificial means tend to have much more of an orange or reddish cast than those found in nature, which are usually a pale yellow. Much of the natural citrine may have started out as amethyst but heat from nearby magmatic bodies may have caused the change to citrine.
Interestingly, a popular gemstone on the market is a mixture of half amethyst and half citrine and is given the name ametrine. The manufacturer takes an amethyst stone and heats it, which converts it to citrine. He then bombards a portion of the stone with beta radiation which converts citrine back to amethyst. By using a metal mask (possibly in the shape of a heart) to block a portion of the beta radiation, an unusual citrine and amethyst gem is produced. Unfortunately for citrine it is often confused with the more expensive orange-yellow topaz and is at times sold as topaz by unscrupulous dealers. This practice has soured many potential citrine fanciers who see citrine as a fake topaz and not as a legitimate gemstone. The finest citrine gemstones have a pure yellow color that cannot be duplicated by golden topaz, which will always have hues of orange or brown to darken the gem.
December
The Birthstone for the Month of December is Tanzanite. Tanzanite is relatively new on the gemstone market, but has left its mark. Its blue-lavender color is rather unique and a wonderful addition to the gemstone palette. Found in Tanzania (hence the name) in 1967, it has since become a well known and widely distributed gemstone. It has become so popular that in October of 2002 the American Gem Trade Association (AGTA) announced that tanzanite had joined zircon and turquoise in the traditional list of birthstones for the month of December. Tanzanite is associated with contentment and understanding.
Tanzanite has better fire than the tourmaline elbaite or peridot and an adequate hardness. Its only one direction of cleavage is somewhat of a problem because it is oriented with the direction of strongest pleochroism. This would be a problem in most gemstones because that is the direction the gem cutter would usually select to maximize the color. However, with tanzanite the color is usually strong enough at any rate. Pleochroism is very pronounced in tanzanite and is seen as three different color shades in the same stone. In the viewing a tanzanite stone, the colors dark blue, green-yellow and red-purple can be seen, all a result of pleochroism. Lesser stones may have a brownish color due to the mixing of blue, purple and green. These stones are usually heat treated to a deep blue color. Iolite is a blue-violet gemstone variety of the mineral cordierite, has strong pleochroism and can be confused with tanzanite. However, iolite is usually less strongly colored, its pleochroic colors vary from blue-violet to yellowish gray to blue and it has less fire. Nearly all tanzanite has been heat treated to generate the beautiful violet-blue color this stone is known for. When first mined, most stones are a muted green color. The only known source of Tanzanite is a five square mile hilltop at Merelani, ten miles south of the Kilimanjaro International Airport in Tanzania.
Zircon’s reputation has suffered of late due to the introduction of a diamond simulant. So for the record, zircon (zirconium silicate, ZrSiO4) is NOT the same material as the artificial gem material Cubic Zirconia (zirconium oxide, ZrO2). However with that in mind, zircon has been used as a diamond simulant both for innocent and nefarious reasons. Zircon resembles diamond in luster and fire and colorless zircons have been mistaken for diamonds by experienced jewelers. Zircon can make a very attractive and affordable gemstone. It is generally found in browns and greens but can be heat treated to beautiful blue and golden colors. Colorless material is produced in this way as well. Zircon is a December Birthstone. It is also one of the Bible stones, as a stone in the third row of the Breastplate of Aaron where it is called a ligure. Zircon is associated with wisdom, honor, and wealth. Zircon is found in many colors, including brown, red, yellow, green, blue, black, and colorless.
Turquoise is a valuable mineral and is possibly the most valuable, non-transparent mineral in the jewelry trade. It has been mined for eons since at least 6000 BC. by early Egyptians. Its history also includes beautiful ornamental creations by Native Americans and Persians. Its popularity is still quite strong today. Although crystals of any size are rare, some small crystals have been found in Virginia and elsewhere. Most specimens are cryptocrystalline, meaning that the crystals could only be seen by a microscope. The finest turquoise comes from Iran but is challenged by some southwestern United States specimens. Turquoise is often imitated by “fakes”, such as the mineral chrysocolla, and poorer turquoise specimens are often dyed or color stabilized with coatings of various resins. The name comes from a French word which means stone of Turkey, from where Persian material passed on its way to Europe.
