7 Most Important Precious Gemstones

When we think of precious gemstones, diamond is usually the first that comes to mind. While diamond is certainly very desirable, accounting for more than 80% of total gemstone sales, it isn’t the single-most significant gemstone. Rather, it’s one of seven important precious gemstones that outshine others with their unparalleled beauty, rarity, and durability. This category includes the Big Three, a trio of the most desirable colored gemstones in the world, comprising ruby, sapphire, and emerald. Of course, the four Cs also determine the value of a gemstone — that is its color, cut, clarity, and carat weight (learn more about this grading system with our guide to the types of diamonds). Another aspect of gemstones that affects their value is provenance, referring to where a gemstone comes from or who previously owned it. However, these precious gemstones aren’t simply the most valuable natural minerals — they’re also the most historically significant.

Here, we first discuss the factors that determine the quality of these gemstones. Then, we dive into the most important precious gemstones in the world and explain what makes them such treasurable artifacts. 

In This Article

• The Four Cs
• Gemstone Species and Varieties
• What’s the Difference Between Precious and Semiprecious Stones?
• What Are the 7 Precious Stones?
  • Diamond
  • Ruby 
  • Sapphire
  • Emerald
  • Alexandrite
  • Opal
  • Pearl

A Guide to the 7 Most Important Precious Gemstones

The Four Cs

The four Cs are industry terms we use to describe the quality of a diamond. They include carat weight, color grade, clarity grade, and cut grade. These terms apply to all gemstones, although other factors also play a role in determining the value of a stone. Emeralds, for instance, are expected to have a cloudy appearance because of their natural inclusions, unlike diamonds, where clarity is prized. This means exceptionally high-quality emeralds can have some inclusions, while the same is not true for diamonds. What’s more, some gemstones are more common in large sizes, such as aquamarine. Fancy color diamonds, on the other hand, tend to be small, and so their worth increases exponentially with size. In all, the four Cs help us understand a gemstone, but they have various implications for different gemstones. 

Carat Weight

Carat weight is the size of a gemstone. Its visual size also depends on the shape, as some shapes are deeper than others, giving it a smaller appearance. Moreover, some shapes have larger surface areas, making the gemstone seem larger. 

Color Grade

As for the color grade, colorless diamonds are graded from D (the most transparent) to Z (the least transparent). The more transparent the colorless diamond, the more valuable it is. Diamonds with yellow undertones are more common and, therefore, less desirable than highly transparent diamonds. Fancy color diamonds are subject to a different grading system that values color saturation. Each colored gemstone has its prized colors, but in general, the more saturated it is, the higher the quality.

Clarity 

Clarity refers to the absence of inclusions in a diamond or other gemstone. This highest clarity grade for diamonds is flawless, meaning there are no noticeable inclusions or blemishes under 10x magnification. Flawless diamonds are incredibly rare and the most covetable. Another desirable clarity grade is internally flawless, referring to diamonds with no inclusions under 10x magnification. Very, very slightly included (VVS) is a more common clarity grade that’s still excellent, broken down into VVS¹ and VVS². These diamonds have tiny inclusions that are invisible to the naked eye and difficult to notice under intense magnification. Other clarity grades exist where diamonds have noticeable inclusions with or without intense magnification, but we recommend VVS² and above. 

As for colored gemstones, the Gemological Institute of America (GIA) groups them into three categories. Type I gemstones are “eye clean,” which means their inclusions are invisible to the naked eye. This is the best clarity grade for colored gemstones, as it’s extremely common for them to have some inclusions under intense magnification. Type II gemstones are usually included, and type III gemstones are almost always included.   

Cut

Another factor affecting a gemstone’s value is cut grade, which refers to the quality of the cutting of the rough. The cut of a gemstone significantly impacts how it reflects light and, in turn, its appearance. On this scale, the finest cut is excellent, and the worst is poor. The cut grade is different from the shape of a gemstone, which is also called the cut. Examples include round, oval, pear, and marquise cuts. 

Gemstone Species and Varieties

Like diamonds, many gemstones are minerals. We distinguish minerals from one another based on their chemical composition and the arrangement of their atoms. Most minerals comprise two or more elements, although the highest-quality diamonds primarily contain carbon. Each mineral has a score from one to 10 on the Mohs scale, which measures the hardness of minerals. 

Gemstone species, also known as mineral species, are broken down into gemstone varieties based on their different trace elements. These trace elements can change the gemstone’s color, and we name certain colors of these mineral species. Emeralds and aquamarine, for instance, are both varieties of the mineral species beryl. Aquamarine receives its blue color from trace amounts of iron. Emerald gets its rich green hue from chromium and vanadium. Corundum is another example of a gemstone species that forms two varieties: ruby and sapphire. If it has red as its primary color, caused by traces of chromium, it’s ruby. All other corundum is considered sapphire. 

What’s the Difference Between Precious and Semiprecious Stones?

Some people categorize stones as either “precious” or “semiprecious,” suggesting that the former is more valuable than the latter. This classification system has become obsolete over the years because today, we know that a stone’s value depends on many factors. A top-tier spinel, for instance, can be more expensive than a lackluster diamond that’s cut poorly and has many inclusions. In this article, we use a holistic approach to identify the most important precious gemstones, highlighting why they’ve held humanity’s interest for centuries.

What Are the 7 Precious Stones?

The most important precious stones are diamond, emerald, ruby, sapphire, alexandrite, opal, and pearl. Below, we delve into where each stone comes from, its characteristics, and its hidden meanings. We also offer shopping tips for each stone, including their price per carat. 

Diamond

Diamond is April’s birthstone and the traditional wedding gift for a 60th wedding anniversary. It’s astrologically associated with those born between March 21 and April 19, making for timeless Aries zodiac jewelry. Natural diamonds formed deep within the earth’s crust thousands of years ago under extreme pressure and heat conditions. This precious gemstone comprises at least 95.95% carbon; the other 0.05% can contain trace elements that impact the color. It is the hardest material on Earth, with a perfect score on the Mohs scale.

Less than 1% of mined diamonds are classified as fancy color, making them a rare natural phenomenon. The rarest colors are pink, red, orange, blue, and green, which contain trace elements, such as nitrogen, boron, and sulfur that give them their color. Colorless diamonds are a traditional choice for engagement rings, although many celebrity brides have opted for fancy color diamonds in recent years. In fact, the most expensive diamond rings mainly showcase fancy pink and blue diamonds. Their hefty price tags testify to how rare and valuable large, fancy color diamonds are. 

A high-quality colorless diamond costs between $3,500 and $10,000 per carat, and fancy color diamonds can reach tens of thousands of dollars. Learn about the factors behind the gemstone’s worth with our guide to why diamonds are so expensive.

Ruby

Ruby is the traditional gift for a 40th wedding anniversary and July’s birthstone. If you’re born during Cancer season, between June 21 and July 22, incorporate rubies into your look as Cancer zodiac jewelry. The word ruby derives from the Latin word ruber, which means “red.” Like sapphire, ruby is a variety of the mineral corundum; these gemstones reflect different colors due to their different trace elements and chemical structures. Corundum with red as its primary color is ruby and all other colors of corundum are sapphire. Traces of chromium cause the reflection of red. Reddish orange corundum is orange sapphire, and reddish purple corundum is purple sapphire.  

The first rubies were mined in the Mogok region of Myanmar (Burma) as early as 3000 BC. However, some experts maintain that rubies are three billion years old. The most covetable rubies are Burmese “pigeon’s blood,” rubies from the Mong Hsu region of Myanmar. According to Hadjibay, “They have been coveted for centuries, but few have had the opportunity to attain them, making their value increase year after year.” Other significant sources of rubies include Sri Lanka, Thailand, and Cambodia. 

Rubies that are red to slightly purplish red are the most valuable; those that lean more into orange or purple are less valuable. Heat treatments are common for removing a ruby’s impurities and enhancing its color, although unheated rubies are more valuable than heated rubies. On the Mohs scale, ruby gemstones score a 9, making them very durable and ideal for ruby jewelry. An unheated, high-quality ruby costs around $3,000 per carat. Burmese rubies can cost hundreds of thousands of dollars per carat.

Sapphire

Comprising September’s birthstone jewelry and Virgo’s zodiac jewelry, sapphire is one of the most important precious gemstones in the world, and it often appears in high jewelry. Sapphire jewelry is the traditional gift for a 45th wedding anniversary gift. The majesty of sapphire gemstones makes them the perfect component of timeless statement pieces. 

As mentioned previously, all colors of corundum are sapphire except red — which is ruby. Blue sapphire can range from very light to violetish blue and medium-dark-toned blue. The most important source of sapphire is the Kashmir Valley in northern India, surrounded by the Himalayas. Kashmir sapphires have intense color saturation and a medium-dark blue hue with a velvety appearance. Their color is dubbed “cornflower blue” because it calls to mind the flower’s blue petals. Sri Lanka and Myanmar are other significant sources of sapphire. Sri Lanka, previously called Ceylon, famously produces padparadscha, a pink-orange sapphire that’s very rare. In the industry, blue Sri Lankan sapphires are referred to as Ceylon, and are generally lighter and brighter than Burmese sapphires. 

Like ruby, sapphires score a 9on the Mohs scale. They’re commonly heat-treated to improve their color, but untreated sapphires are more valuable than treated sapphires. Kashmir sapphires are extremely rare and command upward of $200,000 per carat. “In the gem trade, owning a Kashmir sapphire is a status symbol,” says Hadjibay. An ordinary untreated, high-quality sapphire costs between $2,000 and $10,000 per carat. 

Emerald

Emerald is May’s Birthstone. Those born between April 20 and May 20 can wear emeralds as part of Taurus zodiac jewelry. Emerald jewelry is also the traditional gift for a 20th and 35th wedding anniversary. This important precious gemstone is a variety of the beryl species, a mineral that’s naturally colorless unless it contains chemical impurities that color the stone. Beryl colors include red, pink, blue, and yellow, although proper titles are only afforded to the most precious types of beryl — like emerald and aquamarine. Emerald receives its green color from trace amounts of chromium or vanadium. 

Some experts believe that emeralds are 2.97 billion years old, although the earliest mining records point to ancient Egypt between 3500 BC and 330 BC. Today, the Muzo mines in Colombia are the top source of large, high-quality emeralds. It’s also the most covetable provenance, making Colombian emeralds significantly more expensive than emeralds from other countries. 

Emeralds are known for having jardins, or “garden” in French, referring to their natural inclusions that bring plant foliage to mind; they’re responsible for emerald’s cloudy appearance. “It is quite rare to find an emerald with exceptional clarity,” says Marco Hadjibay, creative director of Bayco Jewels, a high-jewelry brand specializing in rare colored gemstones. As such, emeralds are sometimes enhanced with oil and polymer resins. However, untreated emeralds with few inclusions are the most desirable. The ideal emerald is highly saturated with a green to bluish green color that isn’t too light or dark. Colombian emeralds cost upward of $100,000 per carat, and a typical high-quality emerald ranges from $3,000 to $5,000 per carat. On the Mohs scale, emerald ranks between 7.5 and 8.

Alexandrite

First on the list of the most expensive birthstones in the world is alexandrite. It’s the traditional gift for a 55th wedding anniversary and often appears in June birthstone jewelry and Gemini zodiac jewelry. A variety of the mineral chrysoberyl, alexandrite scores an 8.5  on the Mohs scale. Alexandrite is one of the few gemstones with color-changing properties. In daylight, it reflects a bluish  green hue, and in incandescent light, it showcases a purplish red color; in jest, some jewelers refer to alexandrite as emerald by day and ruby by night. This is not to be confused with play-of-color, which we discuss further in the opal section. Instead, alexandrite is an example of pleochroism, a natural phenomenon where a gemstone reflects various colors from different types of lighting. 

Alexandrite was first mined in 1830 in the Ural Mountains of Russia. Miners discovered it on the birthday of Czar Alexander II and named it after the then-heir to the throne. The original source of alexandrite closed down in 1995. Today, primary sources for the gemstone include Brazil, Sri Lanka, and East Africa, although Russian alexandrite is considered the finest in the industry. Brazilian alexandrite is still very valuable, and it’s known for having better clarity and a more dramatic color change than its Russian counterpart.

The value of an alexandrite is based heavily on the level of color change it projects; the more dramatic the color change, the more desirable and expensive an alexandrite is. Omi Privé, a Los Angeles–based jewelry brand specializing in rare gemstones, tells La Patiala that Russian alexandrites “are most often found in period jewelry since newly mined gems are extremely rare.” As such, a high-quality alexandrite that weighs more than a carat typically ranges between $50,000 and $70,000 per carat. 

Opal

Opal is October’s birthstone. Doubling as Libra zodiac jewelry, opal jewelry is the traditional gift for a 14th wedding anniversary. This gemstone comes in various colors, including white, red, black, and blue-green and is known for displaying a kaleidoscope of colors beneath its surface, called play-of-color. When silica-rich water seeps into rocks and evaporates, it leaves deposits that become opal. This process can take millions of years, and rainfall is usually responsible for carrying the chemical compound underground. 

The finest opals have a deep blue color, although red “fire” opals are extremely rare and also covetable. The main sources of opals are Australia and Ethiopia. Fire opals are most commonly referred to as Mexican opals since Mexico is the primary source of this variety. Black opal is considered to be the most rare and expensive. It has a dark gray or black body that beautifully contrasts opal’s play-of-color. There are only a few known sources of black opal, one of which is in Lightning Ridge, Australia.

On the Mohs scale, opals are usually between 5.5 to 6.5. Jewelers typically fashion opals into a cabochon, a half-dome shape with no facets, which protects this relatively soft gemstone from chipping. It also allows opal’s full range of colors to shine through. A typical, high-quality opal starts at $1,000, while the finest Lightning Ridge opals can cost over $100,000. 

Pearl

Pearl is another birthstone belonging to June, and it’s the traditional wedding gift for a 30th wedding anniversary. This mineral deposit forms within the soft shell tissue of a mollusk. It’s calcium carbonate in crystal form, a mineral that also comprises the shell of a mollusk but in the form of aragonite or calcite. Natural pearls form organically without human intervention. Cultured pearls, on the other hand, result from mollusks that humans intentionally raise to produce pearls. There’s a common misconception that cultured pearls are imitation pearls — but they’re, in fact, genuine pearls. The controlled environment of cultured pearls allows producers to choose the size, color, and quality of pearls for modern pearl jewelry.

Some pearls have interesting organic shapes, such as baroque and drop pearls. This gemstone can also have overtones, a secondary color that floats above the body’s surface color, usually in pink, green, purple, or blue. Another phenomenon that affects a pearl’s color is called orient, meaning it exhibits an iridescent rainbow effect. On the Mohs scale, pearls range between 2.5 to 4.5, meaning they’re very soft and prone to scratching. 

Akoya, Tahitian, and South Sea pearls form in the ocean — a far cry from freshwater pearls farmed in rivers and lakes. Japan and China are leading producers of Akoya pearls, which have a mirror-like effect and a beautiful pink luster. They’re more uniform in color and roundness than other pearls, making them easier to match for a classic string of pearls. Tahitian pearls are rarer and slightly more valuable than Akoya pearls; they come in shades of black and graphite with blue, purple, and green overtones. South Sea pearls come in larger sizes and have a silver- or gold-toned creamy hue. The most expensive pearls are perfectly round and large, although their prices depend on their unique qualities. A high-quality pearl can cost anywhere between $500 and $3,000.