Jewelry & Watches

The Ultimate Guide to the World’s Most Valuable Gems

A glossary of the jewelry industry’s most precious sparklers.

Our desire for beautiful things is as instinctive as it is ancient. Even before the advent of modern civilization, humans used the sparkling gifts of the earth for adornment, and believed them to be imbued with mystical, and even healing powers. These gemstones, which came in every color of the rainbow, were fashioned into jewelry and adored for their luminous beauty, as well as for their capacity to convey wealth and power. Conditions have to be just right to form these crystalline treasures, in a process that sometimes takes hundreds of years. Thus, they are quite rare and therefore, extremely valuable. That they endure, unchanging over time, has likewise made them prized investments, with the most spectacular gems fetching enormous sums.

The most beautiful stones have adorned everything from royal crowns and scepters, to the most gorgeous engagement and wedding rings. Still, one doesn’t really need an occasion to collect fine gems, with the inherent beauty of these sparklers being their own raison d’être. With the global gemstone market estimated to be worth around $17 billion to $23 billion in 2015, there’s no question that it’s thriving. So, from the consummate darlings of haute joaillerie like diamonds, and rubies, to newfound favorites, we take an in-depth look into the glorious world of these shiny wonders. 

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How Gems are Valued

The value of a gemstone depends on a variety of factors, with each type graded against its own standards. That said, a stone’s beauty, rarity, and even durability are huge considerations for gemologists.

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Traditionally, gems have also been classified as either precious or semi-precious, although most agree these are merely guidelines and a deeper assessment of a particular stone is needed to determine its value. Diamonds, sapphires, rubies, and emeralds are categorized as precious stones, with most everything else considered semi-precious. As a general rule, precious stones fetch higher prices, although some semi-precious ones can be quite rare and valuable as well.

Kinds of Gemstones


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One of the most fascinating gems, alexandrite possesses the unique ability to change color depending on the light source. Nicknamed 'emerald by day, ruby by night,' this member of the chrysoberyl family appears green in sunlight, and raspberry red under lamplight.

First discovered in the 1830s in the Ural Mountains of Russia, the gem was named after the heir apparent of the empire, the young Alexander II. It is the birthstone of June, along with the pearl and the moonstone.

What to look for: The more dramatic the change, the more valuable the stone, with the best examples still being the ones mined years ago from Russia. Clarity is also highly prized, as well as the size, as it is quite uncommon to find alexandrites bigger than a carat. 


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Regal and mysterious in rich tones of purple or dreamy in lilac, amethysts have adorned everything from the jewels of monarchy to the rings of bishops. A type of quartz with relatively high hardness, it is the birthstone of people born in February.

It was believed the amethyst could ward off the intoxicating powers of the Bacchus, keeping the wearer clear-headed. In fact, the gem got its name from the Greek word amethystos which meant 'not drunk,' and which is also why during ancient times wine was often served in goblets adorned with amethysts. 

What to look for: The most valuable ones are the ones with a deep reddish-purple or dark purple hue with no visible color zoning or angular zones of a lighter to darker color in a gem. Any coloration of brown or bronze in an amethyst dramatically lowers its value.


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With its cool bluish tint and remarkable transparency, March’s birthstone was named after the Latin phrase 'water of the sea.' It is of the mineral beryl and is often a pastel blue or green-blue with an exceptional luster that really makes it sparkle.

Aquamarine was first thought to be able to calm rambunctious seas, and sailors wore the gem to be safe from harm. In Greek mythology, it was believed to have been washed ashore after spilling from the treasure chests of mermaids. With its luminous appearance of purity, this gem was also believed to be able to enrich marriages with happiness.

What to look for: The ones that are most valued are the ones that naturally exhibit a moderately strong dark blue to slightly greenish blue color, as well as exceptional clarity.


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A pale yellow to brownish orange variety of quartz, citrine’s warm hues evoke images of the sun and are a result of traces of iron present in the mineral. French for 'lemon,' natural citrines are exceptionally rare, with most commercially available ones a result of the heat treatment of pale amethyst (also quartz) to bring out the more desirable yellow hue. Along with topaz, citrine is the birthstone for those who celebrate their birthdays in November.

What to look for: A vivid yellow or reddish-orange color free of brownish tints is most desired in this gem. It is relatively affordable, making it perfect as a big stone for statement jewelry. 


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Formed more than a hundred miles beneath the Earth’s surface billions of years ago, the diamond is arguably the most valuable of the stones. It is the only gem comprised of a single element—carbon—and it is this uniform lattice arrangement of molecules that make it so hard, 58 times harder in fact, than any other substance in nature. Given its enduring quality, it’s no wonder that its name comes from the Greek word adamas, which means 'unconquerable.' It is also the birthstone of people born in April.

It was once believed that Cupid’s arrows were tipped with diamonds, and have always been associated with notions of eternal love. They are extremely coveted in the realm of fine jewelry and are the centerpiece of most modern engagement rings.

What to look for: Developed by the Gemological Institute of America in the 1950s, diamonds are graded based on the 4Cs: color, clarity, cut, and carat.

Color refers to the diamond’s hue, with perfect diamonds being colorless and resembling a drop of water. Clarity refers to the absence of irregularities on the inside of a diamond which are known as inclusions and scratches on its surface, which are known as blemishes. A diamond’s cut refers to how it has been fashioned by an expert gem cutter to reflect light in the scintillating fashion only a diamond can. The cut can also refer to the shape of a diamond. Lastly, carat is largely related to the weight of a diamond with one carat equivalent to two tenths (0.2) of a gram.

Fancy Colored Diamonds

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Gem diamonds in the normal color range of the GIA usually decrease in value with the presence of color. Fancy colored diamonds, on the other hand, become much more prized as the colors become more pronounced. They are created due to certain conditions present when the diamonds were being formed. For example, a tinge of boron makes a diamond blue, while nitrogen turns it yellow.

Extremely rare, the world’s most expensive gems are normally fancy colored diamonds, like the 24.78-carat stone now dubbed as The Graff Pink, which broke auction records when it sold in 2010 for $46 million.

What to look for: For these rainbow-hued stunners, the more brilliant and saturated the color, the better. The most common color is yellow, followed by blue and green ones. Red and pink ones are the rarest. 


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The most well-known member of the beryl family, emeralds exhibit a rich color that ranges from vivid green to greenish-blue. Named for the ancient Greek word for green or smaragdus, its verdant hue is the color of spring and is the perfect birthstone for the month of May.

Emeralds have enjoyed a long history of mysticism and allure. It was one of Cleopatra’s favorite gems, and the ancient Egyptians likewise believed it symbolized fertility and rebirth. In ancient Greek mythology, it was associated with Venus, the goddess of love and beauty. This could well be the reason why some had once believed that wearing an emerald would grant a person the ability to reveal a lover’s true intentions.

What to look for: Emeralds are all about color and the most desirable ones are those with saturated hues of pure green or blue-green. Being quite rare, emeralds are often found with inclusions, which are accepted by the industry and often referred to its internal jardin or garden. Ones without these visible striations, however, are ultimately much more valuable.


Found in almost every color of the rainbow, January’s birthstone is actually a set of closely related minerals that have the same crystalline structure but different chemical compositions. The most common varieties are red and resemble pomegranates, the fruit which was given by Hades to Persephone before she had left him as a token of safety. Thus resulting in garnets becoming symbols of love and commitment in Greek mythology, as well as talismans for safe travel.

And while maroon garnets have always been considered beautiful, rarer shades have spurred a renewed fascination with the stone. Most notable are the orange-red spessartites, the green demantoids and tsavorites, the violet-red rhodolites, and the color-changing garnets.

What to look for: Discovered in the 1960s in the borders of Kenya and Tanzania, tsavorites are the rarest form of the garnet stone. With their intense green color resembling that of emeralds, and unparalleled brilliance, they were popularized in the 1970s by Tiffany & Co. and continue to be coveted to this day.


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Revered for centuries in the East, jade actually refers to two separate minerals—jadeite and nephrite. Best known for its bright green color, and shimmery smooth luster, it also comes in various shades of white, gray, black, yellow, orange, and even violet.

In the Stone Age, people fashioned jade into weapons and tools because of its inherent toughness. But nowhere is this gem most beloved than in China, where this elegant material was transformed into jewelry and carved into intricate masterpieces. The Chinese associate jade with many desirable virtues like purity and prosperity and success, which is why it is still a highly coveted item to this day.

What to look for: Among the two minerals, jadeite is rarer and more durable, making it highly prized. The finest jadeite is almost transparent with a vibrant green color and is known as 'imperial jade,' although other more muted shades of green are also highly favored.

Lapis Lazuli

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Treasured even by ancient civilizations, few would compare to the charm of fine lapis lazuli. A rock comprised of three separate minerals, namely blue lazurite, calcite, and metallic pyrite, it’s long been fashioned into jewelry and decorative objects.

During the Renaissance, it was ground up to create an expensive blue pigment called ultramarine and was used by the most notable artists of that time. It was a paint color so costly that it was often reserved for the clothing of only the most central figures of the paintings, most especially the Virgin Mary.

What to look for: In its best form, lapis lazuli has the most uniform and intense blue to violetish blue hue without any visible calcite. Small, beautifully positioned gold-colored flecks of pyrite also increase its value.


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Ranging from pale blush pink, to subtle apricot, to an attractive light fuchsia, the brilliance and beauty of morganite have made it a favorite for fine jewelry. A cousin of the emerald and aquamarine in the beryl family, these pastel stones were named after financier J.P. Morgan, who had been one of the foremost gem collectors and art patrons in the early 20th century.

What to look for: Although pale-colored ones are highly fashionable and attractive, stronger pinks of this trendy gem are actually rarer.


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Glowing with the light of a thousand galaxies, and showing all the colors of the other gems, fiery opals were once thought by the Romans to be the most precious of all. Arabic legends believed it to have fallen from the heavens in flashes of lightning, but October’s birthstone is actually a product of ancient rains seeping underground carrying with them dissolved silica. These microscopic fragments of silica diffract light into a kaleidoscope of colors.

What to look for: Opals are known for their scintillating rainbow hues known as 'play-of-color.' Precious opals display this beautiful phenomenon where a burst of colors seem to be dancing within the gem, while common opal does not. The more colors are displayed, the better.

All things equal, opals with a base or body color of black are considered more desirable as they show off the many other colors more.


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Pearls are the only gem formed within a living animal and have long been the stuff of legend and lore. The most valuable ones occur in the wild and are called natural pearls. Most pearls now, however, are the product of expert human intervention and are considered cultured pearls.

These glistening orbs are often thought of as white and cream but actually come in a myriad of hues like gray, black, and gold. There are four main types, mainly freshwater, Akoya, South Sea, and Tahitian.

What to look for: A lot of factors come into play when assessing the value of a pearl. The first thing most would consider is the type of pearl, with South Sea ones generally the most expensive. One should also look at its luster or shine, as well as its shape, with round symmetrical ones traditionally commanding more value. A pearl’s size, surface quality, color, nacre thickness, and in the case of creating a necklace, how it matches to other pearls, are also points of consideration.


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Glowing bright with a distinct yellow-green hue, peridot gems were fondly called by the ancient Egyptians as the 'gem of the sun.' Found as nodules in volcanic rock, and even as slivers in meteorites, it is one of the few gems that appear in only one color. It is the birthstone for the month of August and is sometimes also referred to as chrysolite.

What to look for: Most peridots are a vibrant lime green, but the rarer ones exhibit an intense and pure grass green hue.


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Ranging from vibrant pink to dark red, rubies derive their name from the Sanskrit word ratnaraj, which translates to 'king of precious stones.' It has long been considered a potent symbol of wealth and power, and was also believed to bestow their owners with good fortune.

Celebrated as the birthstone of people born in July, it is one of the most valuable gems and can command the highest price per carat of any colored stone. It is also an exceptionally durable gem, with only diamonds and moissanites harder than it on the Mohs scale.

What to look for: All things equal, color is the most important consideration in the valuation of rubies. The most prized ones are an enchanting dark red called Burmese rubies, or pigeon blood rubies.


The birthstone of September, sapphires derive their name from the Greek word sapheiros which means blue. And while sapphires are most commonly associated with these azure tones, they can also be found in various colors of pink, green, orange and the like. In fact, any other stone of the corundum family that isn’t a red ruby can be classified as a sapphire.

Prized for millennia, they are believed to represent royalty and romance, a notion further cemented by the gorgeous Ceylon sapphire engagement ring gifted by Prince Charles to Princess Diana, which was later on bequeathed to Kate Middleton upon her betrothal to Prince William.

What to look for: The best sapphires, irrespective of hue, have vivid and saturated colors, although fancy colored ones are more uncommon. The rarest ones are vibrant orangey-pink stones from Sri Lanka called the Padparadscha Sapphires, which is Sinhalese for 'lotus flower.'


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In ancient Sanskrit writings, spinels were referred to as the 'daughter of rubies.' The two gems resembled each other so closely that many of history’s most famous rubies were actually spinels, like the Black Prince’s Ruby and the Timur Ruby which are both part of the Crown Jewels of England.

In Burma, they are said to be nat thwe or ‘polished by spirits’ because the crystals were so perfect. The birthstone of August, spinels come in pronounced crimson hues, as well as beautiful shades of pink, purple and blue.

What to look for: The most valued spinels are those with vivid red and cobalt blue tones, which is perhaps why they were once confused for rubies and sapphires.


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Found in only one place on earth, the stone is named after its country of origin—Tanzania—where it was discovered in 1967 on the foothills of Mount Kilimanjaro. These velvety blue and purplish stones exhibit a property called pleochroism, which means the gem’s color looks different depending on the viewing direction, which can be maximized to great effect by master gem cutters.

Instantly popular despite its relatively new entry into the gem world, tanzanites are one of the birthstones of December, along with turquoise and zircon.

What to look for: Saturated and bright shades of blue or violet blue are the most prized, as paler versions of the gem are more common.


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Believed to have been from the Sanskrit word ‘tapaz’ which means fire, November’s birthstone comes in a wide range of flamboyant hues from brown to green, orange, red, yellow, pink and purple. Colorless stones can also be heat-treated to transform it into a beautiful blue.

During the Renaissance, it was believed to have been able to dispel enchantment, while the ancient Egyptians believed it had special healing powers.

What to look for: The rarest topaz varieties exhibit vivid red to orange-red hues, known as Imperial Topaz.


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Available in an abundance of attractive shades, from exotic greens and yellows, to vibrant reds and blues, tourmalines are the birthstone of October. It is this plethora of colors that is perhaps the reason for the gem’s etymology, as its name is from the Sinahalese word toramalli which means 'mixed gems.'

Some popular hues have even inspired their own names, like rubellite for the pink to red varieties, and indicolite for the violetish blue and greenish blue ones. Tourmalines also come in multi-colored iterations, with the most popular example being watermelon tourmalines which sport a pink center encapsulated in green.

What to look for: One of the rarest kinds of this gorgeous gem is the Paraiba tourmaline from Brazil, which comes in striking shades of neon blue and green. Its electrifying hue and intense saturation make it highly coveted in the jewelry world, with the blue ones having the most appeal.


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Found in dreamy colors of robin’s egg blue, azure, and sometimes bluish-green, turquoise gemstones are prized for their beauty and rich history. They have been treasured since the time of the ancient Egyptians and Chinese and were crafted into jewelry and amulets by Native Americans.

A rare phosphate of copper found only in the world’s driest and most barren planes, it is one the birthstones of December. It is relatively soft and can be carved into beautiful cabochons, and other ornamental objects.

What to look for: Turquoise is appraised based on three qualities, namely cut, texture, and the presence or absence of impurities. The best examples of this gem are an intense, evenly colored blue, that is often referred to as Persian blue, have a waxy luster when polished, and no thin lines. That said, gems that do have these striations or matrix are called spiderweb turquoise. And while they are not as expensive, those with attractive patterns are also in vogue.

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