The practice of assigning a specific gemstone to each month of the year is a tradition that spans centuries, deeply rooted in ancient history and modern commerce alike. Birthstones serve as a personal talisman for individuals born in a given month, offering a connection to historical lore and geological wonder. The concept has evolved significantly over time, moving from the twelve stones found in the Biblical Breastplate of Aaron to the standardized lists maintained by trade organizations today. These gems are not only prized for their aesthetic beauty and symbolic meanings but are also valued for their durability and unique gemological characteristics. This comprehensive guide explores the complete birthstone chart, delving into the history of these designations, the specific properties of each stone, and the geological sources that bring them to the market.
The Evolution of the Modern Birthstone Chart
The origin of birthstones is most commonly traced back to the Breastplate of Aaron, a ceremonial garment described in the Book of Exodus. This breastplate was adorned with twelve different gemstones, representing the twelve tribes of Israel. Over time, these stones became associated with the signs of the zodiac and eventually evolved into a system linking a specific gem to each calendar month. This transition from religious artifact to personal adornment laid the groundwork for the birthstone tradition known today.
The modern concept of a standardized birthstone list was formalized in the United States in 1912 by the National Association of Jewelers, which is now known as the Jewelers of America. This organization created an official chart to provide consistency for jewelers and consumers, a list that remains the foundation of the modern system. Since its inception, the list has been updated several times to reflect market availability and consumer interest. The first major revision occurred in 1952, which added alexandrite for June, citrine for November, and pink tourmaline for October as alternative options.
Further updates have continued to refine the list. In 2002, the American Gem Trade Association added tanzanite as a new birthstone for December, the first change to the list in 50 years. More recently, in 2016, spinel was added as an additional birthstone for August, providing more color options for those born in that month alongside peridot and sardonyx. These revisions demonstrate that the birthstone chart is not static but is a living tradition that adapts to new discoveries and changing tastes. Beyond the standardized American list, there are significant cultural variations, including the traditional British chart which includes bloodstone for March and rock crystal for April, the Hindu Ayurvedic system based on astrological signs, and the Tibetan mystical chart which features different stones with spiritual significance.
The Birthstone Chart: Properties and Symbolism
The following table, compiled from comprehensive data, provides a detailed overview of the modern birthstones for each month, along with their traditional alternatives, characteristic colors, key symbolism, and hardness on the Mohs scale. This information serves as a quick reference for understanding the essential attributes of each gem.
| Month | Modern Birthstone | Traditional/Alternative | Color | Key Symbolism | Hardness (Mohs) |
|---|---|---|---|---|---|
| January | Garnet | - | Deep Red | Friendship, Trust, Protection | 6.5-7.5 |
| February | Amethyst | - | Purple | Peace, Protection, Tranquility | 7 |
| March | Aquamarine | Bloodstone | Light Blue | Courage, Honesty, Loyalty | 7.5-8 |
| April | Diamond | Rock Crystal | Clear/Colorless | Love, Purity, Strength | 10 |
| May | Emerald | Chrysoprase | Green | Rebirth, Love, Wisdom | 7.5-8 |
| June | Pearl | Alexandrite, Moonstone | White/Cream | Purity, Innocence, Faith | 2.5-4.5 |
| July | Ruby | Carnelian | Red | Passion, Protection, Prosperity | 9 |
| August | Peridot | Spinel, Sardonyx | Lime Green | Strength, Good Fortune, Peace | 6.5-7 |
| September | Sapphire | Lapis Lazuli | Blue | Wisdom, Loyalty, Nobility | 9 |
| October | Opal | Tourmaline | Multicolored | Hope, Creativity, Innocence | 5.5-6.5 |
| November | Topaz | Citrine | Yellow/Orange | Love, Affection, Strength | 8 |
| December | Tanzanite | Turquoise, Zircon | Blue/Purple | Protection, Healing, Wisdom | 6.5-7 |
Detailed Examination of Monthly Birthstones
January: Garnet
Garnet is the designated birthstone for the month of January. While the name "garnet" is most commonly associated with a deep red gem, the garnet group is chemically complex and includes a wide array of colors. Varieties include green (tsavorite and demantoid), orange (spessartine and hessionite), purple (rhodolite), yellow (mali and topazolite), pink (malaya), red (almandine and pyrope), and even black (melanite). Opaque garnets are also typically cut as cabochons. This color variety provides individuals born in January with numerous options beyond the traditional red. The hardness of garnet ranges from 6.5 to 7.5 on the Mohs scale, making it a durable choice for jewelry, though it should be protected from sharp blows.
February: Amethyst
Amethyst is the recognized birthstone for February. It is a variety of quartz, celebrated globally as the most popular purple gemstone. Its color, which can range from a light lavender to a deep violet, is caused by iron impurities and natural irradiation within the crystal lattice. With a hardness of 7 on the Mohs scale, amethyst is sufficiently durable for all types of jewelry, making it a favorite for daily wear. The stone's widespread availability and captivating color have cemented its status as a beloved birthstone.
March: Aquamarine
For the month of March, the primary modern birthstone is aquamarine, a member of the beryl family (which also includes emerald). Its name, derived from the Latin for "seawater," reflects its beautiful range of light blue to blue-green hues. Aquamarine is known for its excellent clarity and durability, with a hardness of 7.5 to 8 on the Mohs scale. This makes it an exceptionally strong and resilient gemstone, ideal for rings and other jewelry that may encounter daily activities. The traditional alternative for March is bloodstone, a dark green chalcedony with red spots.
April: Diamond
Diamond is the birthstone for April, renowned for its unparalleled hardness and brilliance. Scoring a perfect 10 on the Mohs scale, diamond is the hardest known natural material, making it exceptionally resistant to scratching and wear. Its colorless appearance allows it to reflect light with extraordinary fire, symbolizing love and purity. The traditional alternative for April is rock crystal, a transparent variety of quartz. Due to its supreme durability, diamonds are suitable for any type of jewelry setting, including rings and bracelets that are subject to impact.
May: Emerald
The vibrant green gemstone emerald is the birthstone for May. As a variety of the mineral beryl, its distinctive color is derived from trace amounts of chromium and sometimes vanadium. Emeralds typically range in hardness from 7.5 to 8 on the Mohs scale. However, they are often included, meaning they contain internal fractures and inclusions. These characteristics make emeralds more fragile than their hardness might suggest, as they are prone to breakage if struck. Consequently, emeralds require careful handling and protective mountings. The traditional alternative for May is chrysoprase, a green variety of chalcedony.
June: Pearl
June is unique in having three birthstones: the classic pearl, along with alexandrite and moonstone. Pearls are organic gems, formed within the soft tissue of a living mollusk rather than being mined from the earth. Their composition is primarily calcium carbonate. Pearls have a relatively low hardness of 2.5 to 4.5 on the Mohs scale and are susceptible to damage from acids, heat, and abrasion. They require special care to maintain their luster. Alexandrite is a rare variety of chrysoberyl famous for its dramatic color change from green in daylight to red or purplish-red under incandescent light. It is a very durable gem with a hardness of 8.5. Moonstone, a variety of feldspar, exhibits a unique optical phenomenon called adularescence. It has a hardness of 6 but possesses perfect cleavage, making it vulnerable to breakage.
July: Ruby
Ruby, the "king of gems," is the birthstone for July. A variety of the mineral corundum, its red color is caused by the presence of chromium. Ruby is one of the most durable gemstones, with a hardness of 9 on the Mohs scale, second only to diamond. This exceptional hardness, combined with its intense red color symbolizing passion and prosperity, makes ruby an ideal gemstone for all forms of jewelry, including rings and bracelets. The traditional alternative for July is carnelian, a reddish-brown variety of chalcedony.
August: Peridot
Peridot is the primary modern birthstone for August. It is the gem-quality variety of the mineral olivine, known for its distinctive lime green color. The hardness of peridot ranges from 6.5 to 7 on the Mohs scale. However, despite its moderate hardness, peridot is considered to have "fair to poor" durability for jewelry use because it is prone to breakage and is sensitive to rapid temperature changes. The traditional alternatives for August are sardonyx (a variety of onyx) and spinel, which was added to the official list in 2016. Spinel is a highly durable gem with a hardness of 8 and is available in a wide range of colors.
September: Sapphire
Sapphire, the birthstone for September, is another member of the corundum family. While typically associated with a rich blue color, sapphire actually occurs in a rainbow of hues, except for red (which is classified as ruby). With a hardness of 9, sapphire is extremely durable and resistant to scratching, making it suitable for any jewelry application. Its symbolism is tied to wisdom and loyalty. The traditional alternative for September is lapis lazuli, an opaque blue rock composed of multiple minerals, which has a much lower hardness of 5 to 5.5.
October: Opal
October has two birthstones: opal and tourmaline. Opal is a unique and fragile gemstone, prized for its "play-of-color"—a phenomenon where iridescent flashes of color appear as the stone is moved. Its chemical composition is hydrated silica, and it has a hardness of only 5.5 to 6.5 on the Mohs scale. More importantly, opal has a high water content (up to 21%) and is very sensitive to impact and temperature changes, making it one of the more fragile birthstones. The alternative for October is tourmaline. Tourmaline is a much more durable choice, with a hardness of 7 to 7.5 and no cleavage, though it can be brittle. It is known for its incredible variety of colors, earning it the nickname "the rainbow gemstone."
November: Topaz
Topaz is the traditional birthstone for November, with citrine serving as a popular modern alternative. Topaz is a silicate mineral that occurs in a wide range of colors, though it is most often associated with yellow and orange hues. It has a hardness of 8 on the Mohs scale, making it a very durable gem. However, topaz possesses perfect cleavage, meaning it will break easily if struck with significant force in the direction of its cleavage plane. Citrine is a variety of quartz with a hardness of 7, making it a more practical choice for jewelry that will see regular wear.
December: Tanzanite
The final month of the year, December, features tanzanite as its modern birthstone, with turquoise and zircon as traditional alternatives. Tanzanite is a relatively recent addition to the birthstone family, first discovered in Tanzania in the 1960s. It is a variety of the mineral zoisite, known for its striking blue-to-violet or purple hues. Tanzanite has a hardness of 6.5 to 7 but is rated as having "fair to poor" durability for jewelry because it has perfect cleavage in one direction, making it highly susceptible to breaking upon impact. Turquoise is an opaque blue-green mineral (a hydrated phosphate of copper and aluminum) with a hardness of 5 to 6, while zircon (not to be confused with synthetic cubic zirconia) is a durable gem with a hardness of 6.5 to 7.5 but also has perfect cleavage.
Durability and Practical Considerations for Jewelry
When selecting birthstone jewelry, durability is a critical factor, especially for items like rings and bracelets that are exposed to potential impact and abrasion. The Gemological Institute of America (GIA) provides a practical classification for birthstones based on their overall durability.
The most durable birthstones are diamond (April), ruby (July), and sapphire (September), all of which have a hardness of 9 or 10 on the Mohs scale and are suitable for any type of jewelry. Next in durability are aquamarine (March), alexandrite (June), and spinel (August), with a hardness of at least 7.5, making them excellent choices for all settings.
A number of gems are considered durable enough for general use but are subject to scratching and require some care. These include garnet (January), amethyst (February), bloodstone (March), sardonyx (August), tourmaline (October), and citrine (November). For these stones, protective mountings and removing jewelry during strenuous activities are recommended.
Finally, some gemstones are rated as having "fair to poor" durability due to their low hardness, cleavage, or fragility. These include emerald (May), opal (October), peridot (August), and zircon (December), which are all prone to breakage. Moonstone (June), topaz (November), and tanzanite (December) all have perfect cleavage and will break easily if struck. These stones require the most careful handling and are best suited for earrings or pendants rather than rings.
Conclusion
The tradition of birthstones offers a rich tapestry of history, geology, and personal meaning. From the ancient origins of the High Priest's breastplate to the commercially standardized lists of the 21st century, these gems have served as symbols of identity, protection, and personal expression. Each month is associated with a unique stone or set of stones, providing a diverse palette of colors, properties, and lore. Understanding the gemological properties, particularly the hardness and cleavage of each stone, is essential for making informed decisions about jewelry and ensuring these personal treasures can be enjoyed for generations. Whether chosen for their symbolic significance, aesthetic appeal, or durability, birthstones remain a deeply personal and enduring link to the natural world.