A birthstone chart serves as more than a simple reference for jewelry buyers; it is a visual guide to a centuries-old tradition linking specific gemstones to each month of the year. These charts, whether modern or traditional, provide a standardized way to identify the gem associated with a specific birth date. While the concept appears ancient, the modern list of birthstones is the result of a relatively recent standardization process, primarily driven by the National Association of Jewelers (now Jewelers of America) in the early 20th century. Over time, this list has evolved, with additions such as tanzanite for December and spinel for August reflecting changes in availability and consumer interest.
The significance of these stones extends beyond their physical beauty. Each gem carries a rich history of symbolism and metaphysical belief, often rooted in ancient religious texts or historical lore. For example, the deep red garnet, associated with January, has long been a symbol of constancy and protection. Conversely, the brilliant diamond, the birthstone for April, represents innocence and strength, boasting the highest hardness rating on the Mohs scale. This guide explores the geological origins, gemological properties, and cultural meanings of these twelve monthly gems, drawing from a comprehensive analysis of historical charts and gemological data.
Historical Evolution and Standardization of Birthstones
The practice of associating gemstones with specific months is believed to have origins in the Breastplate of Aaron, a ceremonial garment described in the Old Testament of the Bible. This breastplate was set with twelve distinct gemstones, representing the twelve tribes of Israel. Over time, these stones became linked to the zodiac signs and eventually to the calendar months we recognize today. However, the specific stones listed in ancient texts often differ from those on modern charts, leading to a variety of traditional and alternative lists used across different cultures and eras.
The transition to a standardized modern list began in 1912 when the National Association of Jewelers (NAJ) convened to create a consistent chart for the United States. This initial list aimed to provide jewelers with a definitive guide for marketing and design. The original list included stones such as garnet for January, amethyst for February, and diamond for April. Notably, some months featured stones that were not necessarily precious or rare, but were selected for their availability and color suitability. For instance, June was assigned pearl, a biological gem rather than a mineral, reflecting the pearl's immense popularity during that era.
Since the initial 1912 standardization, the list has undergone several revisions to accommodate new discoveries and shifting market trends. The first major update occurred in 1952, when the Jewelers of America added several alternative stones, including alexandrite for June and citrine for November. This revision acknowledged the growing demand for variety and the increased availability of these specific gems. A more recent significant change occurred in 2002 when the American Gem Trade Association (AGTA) added tanzanite as a birthstone for December. This addition was notable as it marked the first change to the official U.S. birthstone list in 50 years, highlighting the dynamic nature of the gem trade.
Further updates continued into the 21st century. In 2016, spinel was added as an additional birthstone for August. This decision was driven by the gem's wide range of colors and its increasing presence in the jewelry market, offering consumers more options beyond the traditional peridot. These evolutions demonstrate that while birthstone charts provide a historical framework, they are not static. They reflect the ongoing relationship between geological discovery, commercial availability, and cultural preference. Different cultures also maintain their own distinct charts, such as the Traditional British chart, which includes bloodstone for March, or the Hindu Ayurvedic system, which is based on astrological signs rather than calendar months.
January: Garnet
The birthstone for January is garnet, a group of silicate minerals that share a similar crystal structure but vary in chemical composition. While commonly associated with a deep red hue, the garnet group encompasses a surprisingly diverse color palette, ranging from the vibrant green of tsavorite to the orange of spessartine. The sources indicate that while red is the most common color, garnets can be found in almost any shade, with blue garnets being the rarest variety, discovered only in the 1990s.
Geological Formation and Sources Garnets form under high-pressure and high-temperature conditions, typically within metamorphic rocks. They are found in a variety of geological environments, often associated with the transformation of sedimentary rocks into schist or gneiss. Major sources for garnet include India, Sri Lanka, and Brazil, though significant deposits are also found in Africa and the United States. The durability of garnet makes it suitable for various jewelry types, and despite the rarity of certain varieties, most garnet species are not considered rare, making them accessible to a wide range of consumers.
Gemological Properties Garnet possesses a reasonably tough hardness rating on the Mohs scale, typically ranging from 6.5 to 7.5, depending on the specific species. This hardness provides good resistance to scratching, though care should be taken to avoid hard impacts that could cause chipping due to the stone's lack of cleavage. The chemical composition varies across the group, but garnets are generally known for their vitreous luster and transparency to opacity.
Symbolism and Lore Historically, garnet has been valued for its symbolic meanings of constancy, friendship, and trust. It was often carried by travelers as a protective amulet against accidents and injuries. The deep red color has also been associated with passion and prosperity in various cultures. According to the provided charts, the key symbolism for January's garnet includes friendship, trust, and protection.
February: Amethyst
Amethyst, the birthstone for February, is a variety of quartz known for its striking purple coloration. The color ranges from pale lilac to deep violet, caused by trace amounts of iron and natural irradiation within the crystal lattice. As a member of the quartz family, amethyst is abundant, though high-quality deep-colored stones are valued more highly.
Gemological Properties Amethyst has a hardness of 7 on the Mohs scale, making it a durable gem suitable for daily wear in rings, pendants, and earrings. It possesses good toughness and no distinct cleavage, making it relatively resistant to breakage. However, prolonged exposure to sunlight can cause fading in some amethyst stones, so proper storage is recommended.
Symbolism and Lore The name "amethyst" is derived from the Greek word "amethystos," meaning "not intoxicated." Ancient Greeks and Romans believed that wearing amethyst or drinking from amethyst vessels could prevent drunkenness and keep the wearer clear-headed and sharp-witted. Over time, the stone's symbolism evolved to include peace, protection, and tranquility. It is often associated with spiritual awareness and calming energies.
March: Aquamarine and Bloodstone
March is associated with two distinct birthstones: aquamarine and bloodstone. The primary modern birthstone is aquamarine, a blue variety of beryl. Its name comes from the Latin for "seawater," reflecting its soothing blue-green hues reminiscent of the ocean.
Gemological Properties of Aquamarine Aquamarine is a relatively hard gem, scoring between 7.5 and 8 on the Mohs scale. It is known for its excellent clarity and transparency, often being found in large, clean crystals suitable for faceting. The color is typically light to medium blue, though deeper blue specimens are more valuable. Its durability makes it an excellent choice for jewelry that is worn frequently.
Bloodstone: The Traditional Alternative Bloodstone, the traditional birthstone for March, is a dark green chalcedony (a variety of quartz) containing red iron oxide inclusions that resemble spots of blood. It is an opaque stone with a hardness similar to other chalcedony varieties, generally around 6.5 to 7. Bloodstone has a long history of use in seals and amulets.
Symbolism and Metaphysical Beliefs Aquamarine is associated with courage, honesty, and loyalty. Historically, sailors wore aquamarine as a talisman for protection against drowning and to ensure safe passage across stormy seas. Bloodstone, conversely, carries symbolism related to vitality and healing. In medieval times, it was believed to have the power to stop bleeding and cure various ailments, linking it to the literal meaning of its name.
April: Diamond
The birthstone for April is the diamond, the hardest known natural material on Earth. Composed entirely of carbon atoms arranged in a diamond cubic crystal structure, its unmatched hardness and brilliance have made it the ultimate symbol of enduring love and luxury.
Gemological Properties Diamond ranks a perfect 10 on the Mohs scale of hardness, meaning it can only be scratched by another diamond. This extreme durability makes it ideal for rings intended for daily wear. The value of a diamond is primarily determined by the "Four Cs": Cut, Color, Clarity, and Carat weight. While most people associate diamonds with colorless stones, they occur naturally in a full spectrum of colors, including yellow, pink, blue, and green.
History and Symbolism The tradition of associating diamonds with April is relatively modern, solidified by the NAJ in 1912. However, the stone's lore dates back centuries. Ancient civilizations believed diamonds were tears of the gods or splinters from falling stars. The stone represents innocence, purity, and strength. Its unbreakable nature is often used as a metaphor for eternal love and commitment.
May: Emerald
Emerald, the birthstone for May, is a vivid green variety of the mineral beryl. Its color is derived from trace amounts of chromium and sometimes vanadium. Unlike many other gemstones, emeralds often contain inclusions and fissures, known as "jardin" (French for garden), which are considered part of the stone's character and proof of its natural origin.
Gemological Properties Emerald has a hardness of 7.5 to 8 on the Mohs scale. However, it possesses poor toughness due to its frequent inclusions and natural fractures. This makes the stone brittle and susceptible to damage from sharp blows or rapid temperature changes. Special care is required when cleaning and setting emeralds; they are often treated with oils or resins to fill surface-reaching fissures and improve clarity.
Symbolism and Lore Emerald has been a symbol of rebirth, love, and wisdom since ancient times. The Egyptians associated it with eternal life and used it in jewelry and burial rites. Cleopatra was famously fond of emerald jewelry. The stone is also linked to the goddess Venus, representing romance and fertility. In modern charts, emerald is associated with happiness and rebirth.
June: Pearl, Alexandrite, and Moonstone
June is unique in having three distinct birthstones: Pearl, Alexandrite, and Moonstone. This variety offers options for different tastes and budgets.
Pearl Unlike other gems, pearl is organic, formed within the soft tissue of a living mollusk. It is the only gem created by a biological organism. Pearls range in color from white and cream to black and iridescent shades. Their hardness is low, typically 2.5 to 4.5 on the Mohs scale, making them soft and prone to scratching. They are sensitive to acids, cosmetics, and perspiration. Pearls symbolize purity, innocence, and faith.
Alexandrite Alexandrite is a rare variety of chrysoberyl famous for its dramatic color change. It appears green or bluish-green in daylight and shifts to red or purplish-red under incandescent light. This phenomenon led to the description "emerald by day, ruby by night." It is a very hard gem, ranking 8.5 on the Mohs scale, making it durable for jewelry. It symbolizes good fortune and intuition.
Moonstone Moonstone is a variety of feldspar known for its adularescence—a billowy, blue or white light that moves across the stone as it is rotated. It is a softer stone, with a hardness of 6 to 6.5. Moonstone is associated with new beginnings, intuition, and balance.
July: Ruby
The birthstone for July is ruby, a red variety of the mineral corundum. Its color ranges from bright "pigeon's blood" red to deeper, darker shades. The presence of chromium is responsible for ruby's vibrant red hue.
Gemological Properties Ruby is one of the hardest gemstones, second only to diamond, with a hardness of 9 on the Mohs scale. This exceptional hardness, combined with its rarity, makes fine rubies extremely valuable—often commanding higher prices per carat than diamonds. Rubies are heat-treated to improve color and clarity, a standard practice in the gem trade.
Symbolism and Lore Historically, ruby has been associated with passion, protection, and prosperity. In ancient India, it was called the "king of gems" and was believed to contain an inner fire that protected its wearer. It is a symbol of power and youthful energy in many cultures. The charts associate July's ruby with passion and protection.
August: Peridot and Spinel
August babies can choose between Peridot and Spinel. Peridot is the traditional birthstone, while Spinel was added in 2016 to provide more color options.
Peridot Peridot is the gem-quality variety of the mineral olivine. It is unique among gems for being found in only one color: an olive green. The intensity and tint of the green depend on the amount of iron present in the crystal structure. Peridot has a hardness of 6.5 to 7. It is often found in volcanic rocks. The stone symbolizes strength, good fortune, and peace.
Spinel Spinel is a magnesium aluminum oxide that occurs in a wide range of colors, including red, blue, pink, and black. For many centuries, red spinel was mistaken for ruby; the "Black Prince's Ruby" in the British Imperial State Crown is actually a massive red spinel. Spinel has a hardness of 8, making it very durable. It is associated with revitalization and hope.
September: Sapphire
Sapphire, the birthstone for September, is a variety of corundum (aluminum oxide) known primarily for its blue color. The blue hue is caused by trace amounts of titanium and iron. While blue is the most famous color, sapphire also occurs in pink, yellow, and green, though these are often specified as "fancy sapphires."
Gemological Properties Like ruby, sapphire is extremely hard, ranking 9 on the Mohs scale. It is highly resistant to scratching and is an excellent choice for rings and bracelets. Sapphires are often heat-treated to enhance their color and clarity, a process that is stable and widely accepted.
Symbolism and Lore Sapphire has long been associated with wisdom, loyalty, and nobility. It was favored by royalty and religious figures as a symbol of divine favor and truth. Ancient Persians believed the earth rested on a giant sapphire, and its reflection colored the sky. In modern charts, sapphire is linked to truth and spiritual enlightenment.
October: Opal and Tourmaline
October is represented by two contrasting birthstones: Opal and Tourmaline.
Opal Opal is a hydrated silica mineral famous for its "play-of-color," an iridescent optical phenomenon that flashes spectral colors as the stone is moved. It is composed of microscopic silica spheres that diffract light. Opal is relatively soft, with a hardness of 5.5 to 6.5, and requires careful handling as it can crack if allowed to dry out (known as "crazing"). It symbolizes hope, innocence, and creativity.
Tourmaline Tourmaline is a complex borosilicate mineral that occurs in more colors and color combinations than any other gemstone. It is often bi-colored or tri-colored within a single crystal. Tourmaline has a hardness of 7 to 7.5, making it more durable than opal. It is known for its ability to generate an electrical charge when heated or pressured (pyroelectricity). It symbolizes protection and healing.
November: Topaz and Citrine
November offers the warm colors of Topaz and Citrine.
Topaz Natural topaz can be colorless, but it is most famous for its imperial yellow to orange-red varieties. It is a hard mineral, ranking 8 on the Mohs scale. Topaz is often associated with love, affection, and strength.
Citrine Citrine is a variety of quartz that ranges from pale yellow to brownish orange. Its color comes from traces of iron. It is a durable stone (hardness 7) and is affordable and widely available. Citrine is often called the "merchant's stone" and is associated with prosperity and success.
December: Tanzanite, Turquoise, and Zircon
December has three birthstones: Tanzanite, Turquoise, and Zircon.
Tanzanite Tanzanite is a variety of zoisite found only in Tanzania. It displays a vivid blue to violet hue and is trichroic, showing different colors when viewed from different angles. It is relatively soft (6.5 on the Mohs scale) and is often heat-treated to achieve its blue color. It symbolizes transformation and higher consciousness.
Turquoise Turquoise is an opaque, blue-to-green mineral composed of copper and aluminum phosphate. It is one of the oldest known gemstones, prized by ancient Egyptians and Native Americans. It has a hardness of 5 to 6 and is porous, making it susceptible to damage from chemicals and lotions. It is associated with protection and healing.
Zircon Zircon is a tetragonal zirconium silicate that occurs in a variety of colors. The blue variety is most popular for December. It is a hard stone, with a hardness of 6.5 to 7.5, and possesses high refractive index and brilliance, often confused with diamond. It is associated with wisdom and spiritual grounding.
Caring for Your Birthstone
Understanding the physical properties of these gemstones is essential for their long-term care. Hardness, as measured on the Mohs scale, is the primary indicator of a stone's resistance to scratching. For example, diamonds, sapphires, and rubies (hardness 9-10) can be worn daily with minimal risk of scratching, though they can still chip due to impact. Softer stones like opal, turquoise, and pearls (hardness 5.5-6.5) require more delicate handling and should be stored separately to avoid abrasion.
Cleaning methods should be tailored to the gem. Harder stones can generally be cleaned with warm water, mild soap, and a soft brush. However, porous stones like pearls and turquoise should not be soaked and should be wiped clean with a damp cloth only. Ultrasonic cleaners are safe for some stones (like diamond and sapphire) but can cause fractures in others (like emerald and opal). Always consult a professional jeweler if unsure about the best cleaning method for a specific birthstone.
Conclusion
The twelve birthstones offer a fascinating window into the geological diversity of our planet and the cultural history of humanity. From the carbon-based hardness of the April diamond to the organic formation of the June pearl, each gem possesses unique characteristics that have inspired centuries of lore and admiration. While the modern birthstone chart provides a standardized guide, it is important to remember the rich evolution of these lists, which blend ancient tradition with modern gemological science. Whether chosen for their symbolic meaning, aesthetic beauty, or geological rarity, these stones remain a personal and meaningful connection to the month of one's birth.