The tradition of associating specific gemstones with each month of the year is a practice steeped in history, religion, and commerce. While the modern list of birthstones is a relatively standardized chart, its origins are complex, evolving from ancient religious texts to a system designed by the jewelry industry to promote sales. Today, birthstones serve as a popular and colorful introduction to the world of gemstones, appealing to a global audience regardless of age, gender, or culture. Each stone carries a unique set of attributes, a rich history, and a distinct place in gemology. This guide provides a detailed exploration of the twelve birthstones, examining their historical journey, geological origins, gemological properties, and the lore that surrounds them.
The concept of birthstones traces its roots back to the breastplate of Aaron, as described in the Book of Exodus. This ceremonial garment was adorned with twelve gemstones, each representing one of the twelve tribes of Israel. Over time, a belief emerged in 1st-century Judea that each of these twelve stones corresponded to a month of the year and a zodiac sign. Wearing the stone associated with the current month was thought to bring good fortune and protection. The modern list as we know it began to take shape in 1912 when the American National Association of Jewelers (now Jewelers of America) standardized a list in Kansas. This list was primarily based on commercial availability rather than historical precedent, though it has been updated several times since. Some months have more than one stone, offering a choice between modern and traditional options. This article will navigate the full spectrum of these precious and semi-precious gems, from the deep red of January's garnet to the vibrant blues of December's trio.
January: Garnet
Garnet, the birthstone for January, is one of the most diverse gemstone groups. It is not a single mineral but a group of several related silicate minerals that share a similar crystal structure but have different chemical compositions. This family includes species like almandine, pyrope, spessartine, grossular, andradite, and uvarovite. The name "garnet" is derived from the early French word grenate, meaning "seedy," a reference to the gem's resemblance to the color and shape of a pomegranate seed.
Historically, garnets were cherished by ancient civilizations. They were used as jewelry by the Egyptians, Romans, and Greeks, and were often worn as protective talismans, particularly by travelers. A popular belief was that garnets could illuminate the night and protect the wearer from evil spirits. In the modern era, garnet was officially designated as the birthstone for January in the 1912 standardization.
While the most common color associated with garnet is a rich, deep red, this gemstone is available in a remarkable spectrum of colors, excluding blue. Green garnets like tsavorite are highly valued, as are the orange and pink varieties known as spessartine and mali garnet. The only garnet known to change color is a rare variety from Madagascar, discovered in the 1990s, which shifts from green in daylight to reddish-purple under incandescent light.
From a gemological perspective, garnets possess a Mohs hardness rating of around 7, making them reasonably tough and suitable for all types of jewelry, including rings. They are mined in various locations across the globe, including the United States, India, and Sri Lanka, with the African continent being a major source for many color varieties.
February: Amethyst
The birthstone for February is the captivating amethyst, a purple variety of quartz. Its color ranges from a pale lilac to a deep, royal purple, caused by the presence of iron and natural irradiation within the crystal lattice. For centuries, amethyst was considered one of the most valuable gemstones, ranking alongside diamonds, rubies, and emeralds in value. This status changed dramatically in the 19th century with the discovery of vast deposits in Brazil, which made the stone more accessible and affordable for a wider audience.
The lore surrounding amethyst is extensive. The ancient Greeks believed the stone could prevent intoxication; in fact, the name "amethyst" comes from the Greek word amethystos, meaning "not drunk." They carved drinking vessels from the gem, believing it would ward off drunkenness. Over time, its symbolic properties evolved. The stone is also said to strengthen relationships and give its wearer courage. At one point in history, amethyst was a gem reserved exclusively for royalty.
Amethyst is a variety of quartz, with a chemical composition of SiO₂ and a Mohs hardness of 7, the same as garnet. It is found in many parts of the world, with major sources including Brazil, Uruguay, and Zambia. Its relative affordability, durability, and beautiful color make it a perennial favorite for jewelry.
March: Aquamarine and Bloodstone
March is represented by two distinct birthstones: aquamarine and bloodstone.
Aquamarine is a variety of the mineral beryl, making it a cousin to emeralds and morganites. Its name is derived from the Latin for "seawater," a fitting description for its serene blue to blue-green hues. The color is caused by trace amounts of iron within the beryl crystal. The finest quality aquamarine is a deep, vibrant blue with minimal green tones. It is a relatively hard and durable gem, with a Mohs hardness of 7.5 to 8, making it an excellent choice for jewelry that will be worn daily. Aquamarine is primarily mined in Brazil, but other significant sources include Nigeria, Madagascar, and Pakistan.
Bloodstone, also known as heliotrope, is a dark green chalcedony (a variety of quartz) characterized by distinctive red spots of iron oxide, which were poetically likened to blood. This opaque gem has a long history of use in seals, signet rings, and amulets. Ancient cultures believed bloodstone possessed powerful healing properties and could staunch wounds, hence its name. It has a Mohs hardness of 6.5 to 7, making it durable enough for most jewelry, though it requires more care than harder gems. Bloodstone is sourced from countries such as India, Brazil, and Australia.
April: Diamond
The birthstone for April is the diamond, the hardest known natural material on Earth. Composed of pure carbon arranged in a diamond cubic crystal structure, its exceptional hardness (10 on the Mohs scale) is a direct result of the strong covalent bonds between its atoms. While most famously associated with colorlessness, diamonds can also occur in a full range of colors, from pale yellow and brown to vivid pinks, blues, greens, and reds.
The diamond has a storied history, revered for its unmatched brilliance and durability. The name "diamond" comes from the Greek word adamas, meaning "invincible" or "unconquerable," a testament to its hardness. Historically, diamonds were believed to possess supernatural powers, offering protection and good health to their wearers. Today, the diamond is synonymous with love and commitment, a tradition popularized by a highly successful marketing campaign in the 20th century.
Diamonds are mined in a variety of locations around the world, with major producers including Russia, Botswana, Canada, and Australia. Their value is determined by the "Four Cs": carat weight, cut, color, and clarity. As the official April birthstone, the diamond remains one of the most popular and valuable gems in the world.
May: Emerald
The lush green emerald is the birthstone for May. It is a variety of the mineral beryl, colored by trace amounts of chromium and sometimes vanadium. The most prized emeralds exhibit a deep, vivid green with a slight bluish undertone. Unlike many other gemstones, inclusions are not only common in emeralds but are often considered a testament to their natural origin. These internal features, sometimes called jardin (the French word for "garden"), are carefully examined by gemologists to determine the stone's authenticity and value.
Emeralds have been mined for over 4,000 years, with the first known source being Cleopatra's mines in Egypt. For centuries, the primary source of the world's finest emeralds was Colombia, known for its deposits in the Muzo and Chivor mines. Today, Colombia, Zambia, and Brazil are the leading producers. With a Mohs hardness of 7.5 to 8, emeralds are durable but require careful handling due to their common inclusions and a tendency toward brittleness. The lore of the emerald is rich, with ancient cultures associating it with fertility, rebirth, and love.
June: Pearl and Alexandrite
June is one of the few months with two official birthstones that offer a stark contrast in appearance and origin: pearl and alexandrite.
Pearl is unique among gemstones as it is organic, created by living mollusks rather than formed in the earth's crust. It is composed of calcium carbonate in the form of aragonite or calcite, laid down in concentric layers. Pearls come in a wide variety of shapes, sizes, and colors, from the classic white and cream to more exotic shades of pink, green, and black. They are among the softest birthstones, with a Mohs hardness of only 2.5 to 4.5, requiring special care to avoid scratches and damage from chemicals. While natural pearls are extremely rare, the market is dominated by cultured and freshwater pearls, making them accessible to all. Major sources include Japan, China, and Australia.
Alexandrite is a rare and remarkable variety of chrysoberyl, famed for its dramatic color-changing ability. It appears green or bluish-green in daylight or fluorescent light and shifts to a reddish-purple or purplish-red under incandescent light. This phenomenon is due to the way the stone absorbs light at different wavelengths. Discovered in Russia's Ural Mountains in the 1830s, it was named after the future Tsar Alexander II. Its colors mirrored the old imperial Russian military colors of red and green. With a Mohs hardness of 8.5, it is a very durable gem, but its rarity makes it one of the most expensive birthstones. Sources outside Russia are now found in Brazil, Sri Lanka, and East Africa.
July: Ruby
The fiery red ruby, the birthstone for July, is one of the most coveted gems in the world. It is a variety of the mineral corundum (aluminum oxide), colored by trace amounts of chromium. The presence of chromium is what gives the ruby its characteristic vibrant red to slightly purplish-red hue. The most prized color is a deep, vivid red known as "pigeon's blood."
Ruby has been revered for centuries, associated with passion, love, and power. Its name is derived from the Latin word rubeus, meaning "red." The finest rubies have historically come from the Mogok region of Myanmar (Burma), and these "Burmese rubies" are considered the gold standard for color. Other important sources include Thailand, Sri Lanka, and Mozambique. Ruby is exceptionally durable, with a Mohs hardness of 9, second only to diamond, making it an ideal choice for all forms of jewelry.
August: Peridot, Spinel, and Sardonyx
August is unique in having three recognized birthstones: peridot, spinel, and sardonyx, offering a choice of color and style.
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 its iron content. Unlike many other gems, peridot is not colored by trace impurities but by its basic chemical composition. It is found in volcanic rock and has been mined for thousands of years. Sources include Arizona in the United States, as well as Pakistan, China, and Myanmar. With a hardness of 6.5 to 7, it is suitable for jewelry but can be prone to chipping if knocked.
Spinel has long been mistaken for other gemstones, most notably ruby. For centuries, the famous "Black Prince's Ruby" in the British Imperial State Crown was actually a large red spinel. This durable gem (Mohs hardness of 8) occurs in a brilliant array of colors, including red, pink, blue, and black. Its vivid reds are particularly prized. Major sources include Myanmar, Sri Lanka, and Tanzania.
Sardonyx is a banded variety of chalcedony, a form of quartz. It combines layers of sard (a reddish-brown chalcedony) and onyx (white or black chalcedony), creating a striking contrast. It has been used for cameos and intaglios since ancient times. With a hardness of 6.5 to 7, it is a relatively affordable and durable gem.
September: Sapphire
The birthstone for September is the sapphire, a classic and regal gem. Like ruby, sapphire is a variety of corundum. While the word "sapphire" typically refers to the blue variety, corundum occurs in every color of the rainbow (except red, which is ruby). These other colors are known as "fancy sapphires" and can be pink, yellow, orange, or green.
The most prized sapphires are a deep, velvety blue. Trace amounts of titanium and iron are responsible for this coveted color. Sapphires have been associated with wisdom, loyalty, and nobility throughout history. They were a favorite of royalty and the clergy. Major sources for blue sapphires include Kashmir (India), Myanmar, and Sri Lanka. With a Mohs hardness of 9, sapphire is an exceptionally durable gemstone, perfect for everyday wear in rings and other jewelry.
October: Opal and Tourmaline
October's birthstones are opal and tourmaline, both celebrated for their incredible diversity of color.
Opal is unique for its "play-of-color," a phenomenon where flashes of spectral light dance across the stone's surface as it moves. This is caused by a network of microscopic silica spheres within the gem's structure. Opals can be "precious," displaying play-of-color, or "common," which are opaque and lack this feature. They come in a wide range of base colors, from white and black to orange and green. Opal is a relatively soft and porous gem, with a Mohs hardness of 5 to 6.5, requiring careful handling to prevent cracking or "crazing." Australia is the primary source for most of the world's opals.
Tourmaline is renowned for its astonishing color range, earning it the nickname "the rainbow gemstone." It is a complex borosilicate mineral that can be found in every color imaginable, often with multiple colors in a single crystal. Pink and red tourmalines are colored by manganese, while green and blue varieties are colored by iron and titanium. Some tourmalines even exhibit a color-change effect. With a hardness of 7 to 7.5, it is a durable gem suitable for jewelry. Key sources include Brazil, Afghanistan, and Africa.
November: Topaz and Citrine
November is associated with the warm and golden birthstones of topaz and citrine.
Topaz is a silicate mineral that occurs in a wide range of colors, including yellow, brown, orange, blue, pink, and red. The most prized color is a rich imperial red-orange. The name "topaz" is thought to derive from an ancient Sanskrit word. It is a hard and durable gem, with a Mohs hardness of 8, making it excellent for jewelry. Topaz is mined in many countries, including Brazil, Sri Lanka, and the United States.
Citrine is the yellow variety of quartz, colored by trace amounts of iron. Its colors range from pale yellow to a deep, honey or brownish-orange. Citrine has been popular since ancient times and is often called the "healing quartz" or "merchant's stone," believed to bring prosperity and success. With a hardness of 7, it is an affordable and durable gem. Large deposits are found in Brazil.
December: Tanzanite, Turquoise, and Zircon
The final month of the year, December, has three birthstones, all featuring shades of blue: tanzanite, turquoise, and zircon.
Turquoise is an opaque, sky-blue to greenish-blue mineral that has been prized for millennia. It is a hydrous phosphate of copper and aluminum, and its color is determined by the amount of copper present. Turquoise is often found in veins or nodules within host rock and is frequently treated to enhance its color and stability. It has a Mohs hardness of 5 to 6. Major sources include Iran, the Southwestern United States, and China. It is one of the oldest known gemstones, revered by ancient cultures for its protective qualities.
Tanzanite is a relatively new discovery, found only in a single small area of Tanzania in the 1960s. It is a variety of the mineral zoisite, and its stunning blue-to-violet hue is the result of heat treatment applied to brownish zoisite crystals. Its color is unlike any other blue gemstone, and its rarity adds to its allure. With a Mohs hardness of 6.5 to 7, it is more delicate than sapphire and requires careful handling.
Zircon should not be confused with the synthetic cubic zirconia. Zircon is a natural gemstone that occurs in a variety of colors, but the blue variety is the most popular for December. It is one of the oldest minerals on Earth, providing valuable information about the planet's geology. Zircon is the birthstone that brings the most brilliance, with a very high refractive index that gives it exceptional sparkle. It is a hard and durable gem, with a Mohs hardness of 7.5. Major sources include Cambodia, Sri Lanka, and Thailand.
Conclusion
The twelve birthstones offer a fascinating window into the worlds of geology, history, and culture. From the ancient belief in their protective powers to their modern status as symbols of personal identity, these gems have captivated humanity for centuries. Each stone, whether a common quartz or a rare diamond, possesses a unique story, a distinct chemical makeup, and a specific place in the natural world. For the enthusiast, the buyer, or the student of gemology, understanding the properties and lore behind each month's stone enriches the experience of owning and wearing these treasures of the Earth.