Birthstones have long captivated humans with their symbolic meanings, aesthetic beauty, and the allure of rarity. While all gemstones possess intrinsic value, certain birthstones stand out due to their exceptional price tags, driven by factors such as color, clarity, carat weight, and historical significance. This article delves into the world of the most expensive birthstones, with a particular focus on Alexandrite, the rarest and most costly among them, as well as other high-value gems like ruby, sapphire, and tanzanite. We will explore their geological origins, cultural and historical significance, and the scientific properties that make them so prized.
The Factors That Determine a Birthstone’s Value
Before diving into the specifics of individual gemstones, it’s essential to understand the key factors that influence a birthstone’s price. According to the sources, the following six elements are most influential:
- Carat Weight: The size of the gemstone plays a significant role in its value. Larger stones are rarer and often more expensive.
- Color: A gemstone’s hue, saturation, and transparency are critical to its desirability. Strong, vivid colors typically command higher prices.
- Brilliance: This refers to the gemstone’s ability to reflect and refract light, which enhances its visual appeal.
- Origin: Certain locations are known for producing particularly high-quality stones. For example, Kashmir is renowned for its sapphires.
- Rarity: The scarcer a gemstone, the higher its value. Alexandrite, for instance, is one of the rarest gemstones in the world.
- Cut and Clarity: The quality of the cut and the presence of inclusions or blemishes also affect a gemstone’s price.
These factors are interrelated and can vary in importance depending on the type of gemstone. For example, while carat weight is a major determinant for diamonds, color and rarity are more crucial for colored gemstones like rubies and alexandrites.
The Most Expensive Birthstone: Alexandrite
A Rare and Enigmatic Gem
Among all birthstones, Alexandrite is often cited as the most expensive. According to source [2], Alexandrite can cost between $15,000 and $70,000 per carat, surpassing even the value of diamonds in some cases. This gemstone, which is one of June’s birthstones (alongside pearl and moonstone), is a variety of the mineral chrysoberyl and is known for its extraordinary color-changing properties.
Alexandrite appears bluish-green in daylight and purplish-red under incandescent light, a phenomenon caused by the way it absorbs and reflects different wavelengths of light. Some jewelers affectionately refer to it as "an emerald by day and a ruby by night." This dual-color display is not only visually striking but also extremely rare—only a few gemstones in the world exhibit such a dramatic change in color.
Historical Origins
Alexandrite was first discovered in 1830 in the Ural Mountains of Russia. According to legend, the gemstone was found on the birthday of Czar Alexander II, the heir to the Russian throne at the time. In honor of this discovery, the stone was named after the young czar. Its red and green hues also correspond with Russia’s military colors, further solidifying its national significance. In fact, it became known as Russia’s national stone.
Despite its historical roots in Russia, natural alexandrite is now extremely rare. Most of the alexandrite available in the market today is synthetic or treated to enhance its color or clarity. Natural alexandrite is so scarce that it is considered one of the rarest and most valuable gemstones in the world.
Geological and Chemical Properties
Alexandrite is a chrysoberyl mineral with a chemical formula of BeAl₂O₄. It is relatively hard on the Mohs scale, with a rating of 8.5, making it durable enough for use in jewelry. Its refractive index is approximately 1.74 to 1.78, and it has a specific gravity of about 3.73, which is relatively high for a transparent gemstone.
What sets alexandrite apart is its color change. This is due to the presence of chromium ions within the crystal structure. In daylight, the chromium absorbs light in the red and yellow wavelengths, making the stone appear green. Under incandescent light, the same chromium ions absorb blue light, allowing the red tones to become more prominent.
Market Value and Collectibility
The scarcity of natural alexandrite and its unique color-changing properties contribute to its high market value. A single carat of high-quality alexandrite can fetch tens of thousands of dollars. Larger stones or those with exceptional color change can command even higher prices. For example, a 15-carat alexandrite in a vibrant color-changing state could easily be worth hundreds of thousands of dollars.
Due to its rarity and beauty, alexandrite is often sought after by collectors and connoisseurs rather than the general jewelry-buying public. Its price is also influenced by the origin of the stone, as natural alexandrite is now primarily found in Brazil and India, with Russia having long since exhausted its natural deposits.
Other High-Value Birthstones
While alexandrite is the most expensive birthstone, several others also command impressive prices due to their rarity, beauty, and historical significance. These include tanzanite, sapphire, ruby, and diamond.
1. Tanzanite – The December Birthstone
Tanzanite, a variety of the mineral zoisite, is the December birthstone and one of the most expensive gemstones. Found only in a small region of Tanzania, tanzanite is prized for its vibrant blue to violet color and its relatively softness (6-6.5 on the Mohs scale). According to source [4], the average price of tanzanite is $1,000,000 per kilogram, with the most valuable stones reaching up to $3.3 million.
Tanzanite’s value is primarily driven by its extreme rarity and the fact that it is limited to a single location. It was first discovered in 1967, and it is estimated that the world’s supply will be depleted within the next few decades. This scarcity, combined with its beautiful color and pleochroism (the ability to display different colors when viewed from different angles), makes tanzanite a highly sought-after gemstone.
2. Sapphire – The September Birthstone
Sapphires, the blue variant of corundum, are the birthstone for September and are known for their exceptional hardness (9 on the Mohs scale) and brilliant color. Source [4] estimates that the average price of sapphire is $1,750,000 per kilogram, with the most expensive examples reaching up to $6.7 million.
The value of sapphires is largely determined by their color depth and origin. The most prized sapphires come from Kashmir, where they are known for their deep, velvety blue color. Other notable sources include 缅甸 (Myanmar), Thailand, and Australia. Sapphires can also be found in a variety of colors, known as "fancy sapphires", including pink, yellow, and green.
Sapphires have been treasured for centuries by royalty and nobility. Their durability and timeless beauty make them ideal for high-end jewelry, including engagement rings, pendants, and brooches.
3. Ruby – The July Birthstone
Ruby, the red variant of corundum, is the July birthstone and is considered one of the most valuable colored gemstones. According to source [4], the average price of ruby is $3,500,000 per kilogram, with the most expensive ruby ever sold reaching $14.2 million. This record was set in 2016 by the 15.99-carat Jubilee Ruby.
The value of rubies is primarily determined by their color intensity and origin. The most coveted rubies come from 缅甸 (Myanmar), particularly from the Mogok region, where they are known for their deep red to "pigeon’s blood" color. Like sapphires, rubies are extremely durable (9 on the Mohs scale) and are often used in high-end jewelry.
Rubies have long been associated with passion, power, and vitality. In ancient times, they were believed to bring protection, prosperity, and good fortune. Today, they remain one of the most sought-after gemstones for collectors and jewelry designers alike.
4. Diamond – The April Birthstone
Diamonds are the April birthstone and have long been considered the ultimate symbol of luxury and status. According to source [3], diamonds typically cost $3,000+ per carat, though their value is heavily influenced by market demand and marketing.
While diamonds are not as rare as alexandrite or ruby, their popularity and cultural significance have driven their high prices. The "Four Cs"—carat weight, color, clarity, and cut—are the primary factors that determine a diamond’s value. Among these, colorless or near-colorless diamonds are the most valuable, as they are the rarest.
Diamonds are also known for their extreme hardness (10 on the Mohs scale), making them ideal for everyday wear in jewelry. They are often used in engagement rings, earrings, and pendants.
The Rarity and Appeal of Other Expensive Birthstones
In addition to the gemstones discussed above, a few other birthstones are also known for their high value and rarity. These include tourmaline and opal, both of which are the October birthstones.
1. Opal – October Birthstone
Opals are known for their iridescent colors and are considered one of the most colorful gemstones. According to source [1], opals can cost between $100 and $4,000 per stone, though some rare examples can fetch $1 million or more. The "Virgin Rainbow Opal" is one such example, valued at $1 million.
The value of opals is largely determined by their color display and pattern. The more colors an opal exhibits and the more vibrant those colors are, the higher its value. Opals are also relatively fragile, as they are water-rich and can lose their color if not properly cared for.
2. Tourmaline – October Birthstone
Tourmaline, the second October birthstone, comes in a wide range of colors, including green, blue, red, and purple. According to source [1], the most valuable tourmaline stones can cost more than $50,000 per carat, with some examples, like the "Ethereal Carolina Divine Paraíba," valued at $125 million.
Tourmaline is a silicate mineral with a glass-like composition similar to quartz. It is relatively fragile, with a Mohs hardness of 7 to 7.5, making it less durable than sapphires or rubies. Despite this, tourmaline is highly sought after for its vibrant colors and unique properties.
Care and Maintenance of High-Value Birthstones
Given their high value and often delicate nature, it is essential to properly care for these gemstones to preserve their beauty and worth.
- Alexandrite and Ruby: These are relatively durable gemstones, with hardness ratings of 8.5 and 9 on the Mohs scale, respectively. They can be cleaned with warm soapy water and a soft cloth, but should be handled with care to avoid scratches from harder materials.
- Sapphire and Diamond: As the hardest gemstones (9 and 10 on the Mohs scale), these can be cleaned with ultrasonic cleaners or steam to maintain their brilliance.
- Tanzanite: Due to its lower hardness (6-6.5) and vulnerability to heat, tanzanite should be cleaned gently and stored separately from other gemstones to prevent damage.
- Opal and Tourmaline: These are more fragile and require special care. Opal should be kept hydrated and avoided from extreme heat, while tourmaline should be stored in a soft pouch and cleaned with a soft cloth and mild detergent.
Conclusion
The most expensive birthstones are not only rare and beautiful but also carry rich historical and cultural significance. Alexandrite, with its dramatic color change and scarcity, stands at the top of this list, followed closely by ruby, sapphire, tanzanite, and diamond. Each of these gemstones has unique properties and values that make them highly sought after by collectors and connoisseurs.
Understanding the factors that influence a birthstone’s price—such as color, clarity, carat, and origin—can help buyers and enthusiasts appreciate the true worth of these gems. Whether for investment, collection, or personal adornment, these high-value birthstones offer a fascinating glimpse into the world of gemology and the enduring allure of precious stones.