The tradition of assigning a specific gemstone to each month of the year is a practice steeped in ancient history, religious symbolism, and modern marketing. While the concept has evolved over millennia, the modern list of birthstones, standardized in the early 20th century, offers a colorful and diverse palette of gems that appeal to a global audience. From the deep red of garnet, which marks the beginning of the year in January, to the vibrant blues of tanzanite and turquoise in December, these stones serve as personal talismans, popular jewelry choices, and fascinating subjects for gemological study. This article provides a detailed exploration of the birthstones for each month, delving into their gemological properties, historical lore, and the journey from ancient traditions to the standardized charts used today.
The origins of the birthstone tradition can be traced back to the Breastplate of Aaron, a ceremonial garment described in the Book of Exodus, which was set with twelve different gemstones representing the twelve tribes of Israel. Over time, these stones became associated with the twelve signs of the zodiac and, eventually, the twelve months of the year. While various cultures developed their own lists, the modern standard was largely established in 1912 by the American National Association of Jewelers (now the Jewelers of America). This list was created to provide a consistent and commercially viable guide for jewelers and has been periodically updated to include new and popular gemstones. Today, enthusiasts often draw from both modern and traditional lists, selecting stones based on color, meaning, or personal preference, creating a rich and varied landscape for personal adornment.
January: Garnet
The year begins with garnet, a gemstone renowned for its association with the color red. However, the garnet group is far more diverse than its common hue suggests. Garnet is not a single mineral but a group of several closely related silicate minerals. This group includes a variety of species, such as almandine, pyrope, spessartine, grossular, andradite, and uvarovite, each with its own chemical composition and color range. While the most familiar color is a deep, rich red, garnets can be found in an astonishing array of colors, including vibrant greens (tsavorite and demantoid), brilliant oranges (spessartine and hessonite), warm yellows (mali and topazolite), and even rare blues.
The gemological properties of garnet are notable for their durability. Garnet has a Mohs hardness rating of approximately 6.5 to 7.5, making it a suitable choice for all types of jewelry, including rings and pendants that are worn daily. Its toughness is also good, and it lacks cleavage, meaning it is less likely to chip or break when struck. The chemical formula for the garnet group is complex, typically represented as X3Y2(SiO4)3, where X and Y are elements like calcium, magnesium, iron, or aluminum. This variability in composition is what gives rise to its wide color spectrum. Historically, garnet was believed to protect travelers from harm and to symbolize friendship and trust. Its name is derived from the Latin word granatum, meaning pomegranate, due to the resemblance of its crystals to the fruit's seeds.
February: Amethyst
Amethyst, the birthstone for February, is the most popular and well-known variety of quartz. Its color, a captivating purple, ranges from a pale lilac to a deep, saturated violet. The color is primarily caused by trace amounts of iron within the quartz's crystal structure, along with natural irradiation. As a member of the quartz family, amethyst has a chemical composition of silicon dioxide (SiO2) and a Mohs hardness of 7, making it a durable and relatively easy gemstone to care for.
Historically, amethyst was considered a gem of royalty and was highly valued, often commanding prices on par with ruby and emerald. Ancient Greeks believed the stone could prevent intoxication, and its name is derived from the Greek word amethystos, meaning "not drunk." This lore led to the creation of drinking vessels carved from amethyst. However, with the discovery of large deposits in Brazil in the 19th century, the stone became much more accessible and its value decreased, though its beauty and rich symbolism have kept it a perennial favorite. Amethyst is mined in various locations around the world, with major sources including Brazil, Uruguay, Zambia, and Namibia.
March: Aquamarine and Bloodstone
March is associated with two distinct birthstones: aquamarine and bloodstone. Aquamarine is the modern choice, a transparent variety of the mineral beryl, which also includes emerald and morganite. Its name is derived from the Latin for "seawater," a fitting description for its beautiful blue to blue-green color. The color of aquamarine is caused by trace amounts of iron. It is a relatively hard gemstone, with a Mohs hardness of 7.5 to 8, and has excellent clarity, with inclusions being rare. Aquamarine is often found in large, clean crystals, making it popular for statement jewelry. Major sources for aquamarine include Brazil, Nigeria, Madagascar, and Pakistan.
The traditional birthstone for March is bloodstone, an opaque, dark green chalcedony (a variety of quartz) characterized by red spots of iron oxide, which were thought to resemble blood. This cryptocrystalline quartz has a hardness of 6.5 to 7. Bloodstone has a long history, having been used for seals and amulets in ancient times. It was believed to have healing properties and to bring strength and courage to its wearer.
April: Diamond
The diamond, birthstone for April, is arguably the most famous and coveted gemstone in the world. Composed of pure carbon, diamond is the hardest known natural material, rating a 10 on the Mohs scale. This extreme hardness, combined with its high refractive index and strong dispersion (the property that causes "fire" or flashes of color), gives the diamond its unparalleled brilliance and sparkle.
While diamonds are most often associated with colorless or white stones, they occur in a full spectrum of colors, including yellow, brown, blue, green, pink, and red. The value of a diamond is determined by the "four Cs": cut, color, clarity, and carat weight. The cut of a diamond is particularly critical, as it dictates how well the stone interacts with light. Major sources for diamonds include Russia, Botswana, Canada, the Democratic Republic of Congo, and Australia. Historically, diamonds have been symbols of eternal love and commitment, a tradition popularized in the 20th century through masterful marketing campaigns. The traditional birthstone for April is also the diamond, making it a consistent and powerful choice.
May: Emerald
Emerald, the birthstone for May, is a member of the beryl family and is prized for its brilliant, deep green color. The captivating hue is caused by trace amounts of chromium and sometimes vanadium. Like aquamarine, emerald has a Mohs hardness of 7.5 to 8. However, emeralds almost always contain inclusions and surface-reaching fractures, a condition known as jardin (French for "garden"). These characteristics are often accepted as part of the stone's unique beauty and are evidence of its natural origin. In fact, the gemological community often employs a more lenient grading for clarity in emeralds compared to other colored stones.
The most prized emeralds come from Colombia, known for producing stones with a unique and highly desirable green hue. Other significant sources include Zambia, Brazil, and Zimbabwe. Emerald has a rich history, revered by ancient civilizations like the Egyptians, who mined it as early as 3500 BCE. Cleopatra was famously fond of emeralds and wore them in her royal adornments. The stone has long been associated with rebirth, fertility, and immortality.
June: Pearl and Alexandrite
June is unique in having three birthstones: pearl, alexandrite, and moonstone. The most traditional of these is the pearl. Unlike all other gemstones, pearls are organic, formed within the soft tissue of a living mollusk. They are composed of calcium carbonate in the form of aragonite or calcite. Their lustrous appearance is a result of light reflecting off the many microscopic layers of nacre. Pearls are relatively soft, with a Mohs hardness of just 2.5 to 4.5, making them susceptible to scratches and requiring gentle care. Their color is typically white or cream, but they can also occur naturally in shades of pink, silver, and black. While natural pearls are extremely rare and valuable, most pearls on the market today are cultured, grown in pearl farms with human intervention.
The modern birthstone for June is alexandrite, a rare and fascinating variety of chrysoberyl. Alexandrite is famous for its dramatic color-changing ability, appearing green or bluish-green in daylight and fluorescent light, and shifting to a brownish-red or purplish-red under incandescent light. This phenomenon is due to the way the stone's crystal structure absorbs light. Alexandrite has a high hardness of 8.5, making it very durable. It was first discovered in Russia's Ural Mountains in the 1830s and was named after the future Tsar Alexander II. The stone's red and green colors were said to mirror the old imperial Russian military colors.
July: Ruby
Ruby, the birthstone for July, is one of the most valuable gemstones, commanding the highest per-carat price for any colored gemstone. A member of the corundum mineral family, ruby is essentially the red variety, while all other colors of corundum are classified as sapphire. The vibrant red color is caused by the presence of chromium. The most prized color for a ruby is a deep, rich red with a slightly purplish hue, often described as "pigeon's blood."
Ruby is an exceptionally durable gemstone, with a Mohs hardness of 9 and excellent toughness. The most historically significant source of rubies is the Mogok region of Myanmar (formerly Burma), which has been producing gems for centuries. Other important sources include Thailand, Cambodia, and Mozambique. The name "ruby" comes from the Latin word rubeus, meaning red. Throughout history, the ruby has been a symbol of passion, protection, and prosperity.
August: Peridot and Spinel
August has two modern birthstones: peridot and spinel, along with the traditional stone, sardonyx. Peridot is the gem-quality variety of the mineral olivine. It is one of the few gemstones that occurs in only one color: a distinctive lime green. The shade can vary from yellowish-green to a more intense olive green, depending on the amount of iron present. Peridot has a Mohs hardness of 6.5 to 7. It is believed to have been one of Cleopatra's favorite gemstones, though she often confused it with emeralds. Peridot is found in many locations around the world, with significant deposits in Pakistan, Myanmar, and Arizona in the United States.
Spinel is a separate mineral group with the chemical formula MgAl2O4. It has a Mohs hardness of 8 and comes in a wide range of colors, including red, pink, blue, violet, and black. For centuries, red spinel was mistaken for ruby, with many famous "rubies" in royal collections, such as the Black Prince's Ruby in the British Imperial State Crown, actually being large spinels. The name spinel is thought to come from the Greek word spinos, meaning spark, likely referring to its fiery appearance.
September: Sapphire
Sapphire, the birthstone for September, is the blue variety of the corundum mineral family. While corundum can occur in every color except red (which is ruby), the term "sapphire" is most commonly associated with the blue stones. The iconic blue color is caused by trace amounts of titanium and iron. Sapphire is a very hard and durable gemstone, with a Mohs hardness of 9, making it an excellent choice for all types of jewelry.
The most prized color for a sapphire is a deep, velvety blue known as "cornflower blue." The most famous source for sapphires is Kashmir, a region on the border of India and Pakistan, which produced a limited supply of gems with a unique velvety texture in the late 19th and early 20th centuries. Other major sources include Myanmar, Sri Lanka, Madagascar, and Australia. Sapphires have long been associated with royalty and romance and are said to symbolize wisdom, loyalty, and nobility.
October: Opal and Tourmaline
October is represented by two birthstones: opal and tourmaline. Opal is a unique and captivating gemstone known for its "play-of-color," a phenomenon where flashes of iridescent light dance across the stone's surface as it is moved. This effect is caused by the diffraction of light from a network of microscopic silica spheres within the stone's structure. Opal is composed of hydrated silica and has a Mohs hardness of 5.5 to 6.5, making it relatively delicate and requiring careful handling. It is also known for its "potch," or common opal, which lacks play-of-color and is opaque. Australia is the primary source for most of the world's precious opal.
The other October birthstone is tourmaline. Tourmaline is a complex borosilicate mineral known as the "Rainbow Gemstone" because it occurs in more colors and color combinations than any other gemstone. Its chemical complexity allows for a vast array of hues. Some tourmalines even exhibit a single stone with multiple colors, such as the watermelon tourmaline with its pink center and green rind. Tourmaline has a good hardness of 7 to 7.5, making it more durable than opal. Major sources for tourmaline include Brazil, Afghanistan, and parts of Africa.
November: Topaz and Citrine
November's birthstones are topaz and citrine. Topaz is a silicate mineral that occurs in a wide range of colors, but it is most famously associated with a rich golden yellow or orange. The most prized color is a deep "Imperial Topaz," a reddish-orange shade. Topaz has a Mohs hardness of 8, making it a durable gem. However, it has perfect basal cleavage, meaning it can be split along certain planes if struck with sufficient force, so it requires care in jewelry setting. The most significant sources for topaz are Brazil, Nigeria, and Sri Lanka.
Citrine is the yellow to orange variety of quartz. Its color is caused by traces of iron. With a Mohs hardness of 7, it is a durable and popular gemstone. Citrine is often more affordable than many other colored gems and is widely available in large sizes. It is sometimes referred to as the "healing quartz" or "merchant's stone." Major sources for citrine include Brazil, Bolivia, and Spain. It is worth noting that topaz and citrine are sometimes confused in the market, as they can have similar colors, but they are entirely different minerals.
December: Tanzanite, Zircon, and Turquoise
December has three birthstones: tanzanite, blue zircon, and turquoise. Tanzanite is the most modern of the three, having been discovered in Tanzania in the 1960s. It is a variety of the mineral zoisite and is known for its mesmerizing blue-to-violet hue. The color is the result of heat treatment, which is applied to most tanzanite found in nature. With a Mohs hardness of 6.5 to 7, it is moderately durable. Tanzanite is found in only one location in the world: the Merelani Hills of northern Tanzania, making it a truly single-source gemstone.
Blue zircon is the traditional birthstone for December and is one of the oldest known gemstones. It is a naturally occurring mineral (zirconium silicate) that should not be confused with the synthetic cubic zirconia used in jewelry. Zircon has a high refractive index, giving it a brilliant sparkle similar to that of a diamond. It has a Mohs hardness of 6.5 to 7.5 but can be brittle. Most blue zircon on the market has been heat-treated to achieve its color. Major sources include Cambodia, Sri Lanka, and Thailand.
Turquoise is an opaque, blue-to-green mineral (a hydrous phosphate of copper and aluminum) that has been prized for thousands of years. It is not typically faceted but is cut into cabochons for beads and inlays. Turquoise has a Mohs hardness of 5 to 6 and is porous, so it can be damaged by chemicals and oils. Its color is determined by the amount of copper (blue) or iron (green) present. The most famous source is the Persian Plateau (modern-day Iran), but it is also mined in the southwestern United States, China, and other locations.
Conclusion
The twelve birthstones of the year represent a remarkable cross-section of the mineral kingdom, from the organic luster of pearl to the crystalline hardness of diamond. Each stone offers a unique combination of color, durability, and history, providing a personal connection to the natural world for those born in its corresponding month. The journey from ancient mystical beliefs to the modern, commercially driven lists illustrates the enduring human fascination with these beautiful minerals. Whether chosen for their symbolic meaning, their aesthetic appeal, or their geological rarity, birthstones remain a vibrant and significant part of gemology and personal adornment.