35 Most Valuable Gemstones, From Least to Most Expensive

What are the world’s most valuable gemstones? And just how expensive are they?

Most Valuable Gemstones, From Least to Most Expensive

When you think of expensive gemstones, what comes to mind? Most people think of the Big Four: diamonds, emeralds, rubies and sapphires. However, it might surprise you to know that there are precious stones that are rarer and more expensive than these popular ones.

A number of the most valuable gemstones are new discoveries that have only been found in recent decades. Minerals such as Pezzotaite, which was discovered in 2002, or Musgravite, the first gem-quality stone that was found in 1993, are relative newcomers to the gemstone field. Yet they are growing in popularity. Their high value comes from their scarcity due to small deposits, huge demand or the fact that they may only be mined in one or two places in the world.

Some stones, such as aquamarine, have been popular since antiquity, and top-quality specimens command high prices. More unusual stones, such as black diamonds, are becoming popular and pricey due to the influence of celebrities wearing them.

No matter the reason for their price, here are the 35 most valuable gemstones in the world, ranked by their price per carat weight. And, yes, this list does include diamonds, emeralds, rubies and sapphires.

35. Amblygonite

Price per carat:$51-$108.08

Highlights: Amblygonite is usually a light straw color, but it occasionally displays more vibrant shades of yellow, green, blue-green and even lilac.

What Makes Amblygonite So Valuable

Amblygonite is too soft to use for most jewelry, particularly rings, but vibrantly colored amblygonite stones are prized by collectors, like many valuable collectibles, due to their rarity.

Large faceted stones are even less common.

The Most Expensive Amblygonite in the World

Amblygonite might not look like much to the untrained eye, but a stone of this size is quite a find. This is an example of a raw, natural amblygonite stone found in Minas Gerais, Brazil.

Measuring over 3 inches across and weighing almost 13 ounces, the semi-translucent stone was valued at $680.

34. Enstatite

rough Bronzite (Enstatite) rock isolated on white

Price per carat:$59-$81

Highlights: Enstatite is a fairly common silicate mineral ranging in color from clear to gray, yellow, brown or green. The most common variety is known as bronzite because of its brownish color, but green pieces from South Africa or Myanmar are much more rare and costly.

What Makes Enstatite So Valuable

Bronzite (Enstatite) on a white background

Enstatite isn't an ideal stone for jewelry due to its low rating of five to six on the Mohs hardness scale. In its green form, however, it's beautiful enough to be considered a rare gemstone.

These samples are rarely found outside of Kimberley, South Africa, but more common versions can be found in several other regions, including Austria, India, Germany, Greenland, Mexico and California.

The Most Expensive Enstatite in the World

While the reddish-orange version of Enstatite is usually the most valuable, this chartreuse stone was worth $1,599.99 thanks to its unmatched clarity and vibrant green coloration.

Many Enstatite stones have heavy inclusions, or materials, trapped inside. This one has very few, which is another reason for its unusually high price.

33. Axinite

Price per carat:$59-$540

Highlights: Axinite is considered a rare mineral from the borosilicate group. Its color varies from gray to brown or purple.

What Makes Axinite So Valuable

Axinite is hard enough to be cut and used in jewelry that's highly resistant to scratches. It's not as durable as very hard gemstones like diamonds, however, and can shatter if subjected to hard impacts.

Even though it's rarely completely clear, it's valuable because of how uncommon it is.

The Most Expensive Axinite in the World

While finding the most expensive axinite specimen in the world is tougher than with more well-known gemstones, this purple axinite gem from Tanzania is remarkably clear with excellent color and a $450 price tag.

32. Kornerupine

Kornerupine is a very rare gemstone — A rich emerald green Kornerupine crystal on white

Price per carat:$64.53-$121.57

Highlights: Kornerupine, also called prismatine, is a borosilicate mineral that can be brown to yellow in color. It's a seven on the Mohs hardness scale and was first discovered in 1884.

What Makes Kornerupine So Valuable

Kornerupine is considered to be a gemstone when it's found in its clear green and yellow shades.

Bluish-green kornerupine stones are worth the most, but emerald green stones are valuable as well.

The Most Expensive Kornerupine in the World

This 1.3-carat kornerupine gemstone is a prime example of the bluish-green color that gives the gemstone the most value.

It's extremely rare, and this particular stone was valued at $1,599.99. It was found in Tanzania, and it displays different hues depending on the angle the light hits it.

31. Hiddenite

Price per carat:$100 on average

Highlights: Hiddenite can vary in price drastically depending on the cut, clarity and color of the stone. The deeper the shade of green, the more it's worth.

Custom-cut gems with high clarity are worth the most, but cutting them is a challenge. Like diamonds, if they're cut at the wrong angle, they'll shatter.

What Makes Hiddenite So Valuable

Hiddenite, named after W.E. Hidden who discovered it in the late 1800s, looks ordinary in the picture here.

Some specimens can be a deep emerald green, and in this case, some experts consider it to be even more brilliant than that of a real emerald.

The Most Expensive Hiddenite in the World

Take a look at this beauty. While Hiddenite is usually one of the lower-priced minerals, this crystal from Afghanistan was so uncommonly large and unique in color that it was valued at $5,500.

The mix of greens, blues and purples is unreal.

30. Pearl

Price per pearl: $300-$1,500

Highlights: South Sea pearls are considered the "Rolls Royce" of pearls, and a strand can cost up to $100,000.

What Makes Pearl So Valuable

While pearls are considered gemstones, they are not minerals but made of calcium carbonate by mollusks, such as oysters. Pearls have been popular since antiquity, especially with royalty.

Good-quality pearls are long-lasting and hold their value well. Pearl jewelry is often passed down in families as heirlooms.

The Most Expensive Pearl in the World

The most expensive pearl known was found by a fisherman near Palawan, in the Philippines, measures 26 inches and is valued at $100 million.

It looks more like a giant conch shell than a smooth, round pearl. It weighs about 75 pounds and the fisherman who found it kept it hidden under his bed for 10 years.

29. Red Coral

Price per carat: $320

Highlights: True red coral is rare and becoming hard to find.

What Makes Red Coral So Valuable

Coral, especially red coral, is considered a gemstone, although the source is organic. It’s made as a branching plant-like structure by marine creatures that live in colonies.

Coral comes in shades of white, pink and red, and the value of a piece is determined by its hue and color saturation.

The gem has been popular since antiquity and is often made into carvings and statues as well as jewelry.

The Most Expensive Red Coral in the World

Japanese red coral, known as "ox blood," is the rarest and most in demand, usually by wealthy Chinese.

Since red coral is made organically, there's no giant gemstone to be unearthed. Chinese demand for the gemstone has increased dramatically, and it has been overharvested, with the Mediterranean's red coral colonies now producing only 25 percent of what they should.

28. Tanzanite

Price per carat: $600-$1,000

Highlights: Tanzanite is found only in one place in the world, and the supply will be gone in 20 years.

What Makes Tanzanite So Valuable

Generally, Tanzanite (or Zoisite) is found in a reddish brown that is heat-treated to turn the stone sapphire blue, amethyst or violet. Heat treatment deepens the blue color saturation but doesn’t affect the price of the gems, as this is known to be part of the process.

The mineral is found only in the foothills of Mount Kilimanjaro in Tanzania, which accounts for both its name and its rarity. The supply of Tanzanite will likely be finished in the next 20 years.

The Most Expensive Tanzanite in the World

The most expensive pieces of Tanzanite in the world were found by a small-scale diamond miner.

The most expensive one weighed nearly 20.5 pounds, and the second-most expensive Tanzanite weighed 11.3 pounds. He sold both of them to the Tanzania government for $3.3 million.

27. Aquamarine

Price per carat: $1,000

Highlights: One of the most popular gemstones since antiquity, aquamarines are prized for their natural blue color.

What Makes Aquamarine So Valuable

Aquamarines are a light to intense blue, or green-blue, form of the mineral beryl. The darker the blue, the more expensive the stone. Aquamarine has been popular since antiquity and was believed to calm waves and keep sailors safe as well as cure many illnesses.

The stones are popular in Asian countries where they are thought to have good energy for Chinese geomancy (feng shui.) Deep blue stones are very rare and expensive, and found only in Brazil.

Aquamarines are also found in Africa, Pakistan, Russia and Afghanistan.

The Most Expensive Aquamarine in the World

The most expensive aquamarine in the world is the Dom Pedro aquamarine.

Discovered in the 1980s, this huge aquamarine was originally 200 pounds, but it was dropped by Brazilian miners and broke into three pieces. Two were broken down further and cut for jewelry, while the third piece was named Dom Pedro after Brazil's first emperor.

It is now on display at the Smithsonian National Museum of History. It's 10,363 carats (about five pounds) and is worth $5 million to $6 million.

26. Sapphire

Price per carat: $1,200-$2,000

Highlights: Sapphires are the second-most popular stones after diamonds and have sold for up to $135,000 per carat.

What Makes Sapphire So Valuable

Sapphires, like rubies, are made from corundum, which is a form of aluminum oxide, one of the hardest substances known in existence. While most people think of sapphires as being blue, the stones also come in yellow, green, orange, black and pink. For non-blue stones, the color is included in the name, such as the yellow sapphire.

Sapphires are mined in many countries around the world. The most expensive sapphires are the largest in size with the deepest color saturation.

The Most Expensive Sapphire in the World

The most expensive sapphire ever sold was $135,000 per carat.

It's known as the Blue Belle of Asia, a 392.52-carat stone that sold for $17.56 million in 2014 to an unidentified buyer at a Christie's auction in Geneva. The stone was set on gold with a diamond-tasseled necklace.

The stone was first discovered in 1926, in Ratnapura, Sri Lanka.

25. Spessartine Garnet

Price per carat: $1,500-$3,000

Highlights: Spessartine is an extremely rare form of garnet.

What Makes Spessartine Garnet So Valuable

Spessartine is a form of garnet that is colored with manganese and aluminum. The mineral was first discovered by mineralogist F. Bedano in Spessart, Bavaria, in the early 1990s, and it was named after where it was found. The natural color of this stone is a bright orange to reddish-orange to brownish-orange.

"Mandarin garnet" specimens are the most in demand and the most expensive. Spessartine gem quality stones are rarely larger than 5 to 7 carats in weight. The mineral is also found in Africa, India, Pakistan, China, Afghanistan, Brazil, Myanmar and the U.S.

The Most Expensive Spessartine Garnet in the World

While spessartine is rare and expensive, there aren't many big, expensive examples of this brilliant red-orange stone.

One of the most expensive single spessartine garnets we could find sold for $31,250 at a Bonhams auction in 2012. Another, a ring by Bulgari, sold for roughly $61,000.

23. Jeremejevite (Tie)

Price per carat: $2,000

Highlights: Jeremejevite is rare, and gem-quality stones over 1 carat are almost never found.

What Makes Jeremejevite So Valuable

Jeremejevite is a rare aluminum borate mineral similar to quartz. Stones come in shades of blue, from violet to cornflower, as well as clear, yellow and brown.

The mineral was first discovered in the Andun-Chilon Mountains in Siberia by a Russian mineralogist and engineer, Pavel V. Jeremejev, after whom it is named.

The main source of jeremejevite is Namibia, but it’s also found in Russia, Myanmar, Germany and Tajikistan.

The Most Expensive Jeremejevite in the World

The most expensive jeremejevite in the world must belong to Joseph Fam, a Singapore resident who owns the largest cut jeremejevite in the world. It weighs 45.61 carats and was measured in July 2017, according to the Guinness Book of World Records.

The true value of this stone can't be found. But if we go by the stone's per-carat price, it's worth about $91,000.

23. Pezzottaite (Tie)

Price per carat: $2,000

Highlights: Pezzottaite is a new gemstone, discovered in 2002, that is only found in two places in the world. The supply has failed to keep up with demand, and prices are rising.

What Makes Pezzottaite So Valuable

Pezzottaite is a new gem mineral that was discovered in 2002 in Madagascar. The stone is named after Dr. Federico Pezzotta, a geologist and mineralogist who studied granite formations on the island.

Although this stone is sometimes called "red beryl," pezzottaite isn’t a beryl at all but actually a silicate formed by cesium, beryllium, lithium and aluminium.

Pezzottaite is usually a rich pink, often raspberry, color and can sometimes be found with orange or purple hues. The stone is also mined in Afghanistan.

The Most Expensive Pezzottaite in the World

Being a relatively new gemstone, pezzottaite isn't the most well-known gem in the world, and there aren't any famous brooches made with the stone.

According to the French Gemmology Laboratory, a 59.98-carat was discovered in 2004. If that gemstone sold at today's prices, it would fetch nearly $120,000.

22. Fire Opal

Price per carat: $2,300

Highlights: Good-quality fire opals are a rare find.

What Makes Fire Opal So Valuable

Fire opals are translucent and contain shades of green, yellow, orange, red and gold. As the stone moves, the colors appear to sparkle and shift, called a "play of color." The fire opal is rarer than other types of opal, especially in gem-quality stones.

While the background of a fire opal is milky or translucent white, the colors depend on which minerals were present when the stone was formed.

Mexico is the largest source of fire opals, although they’re also found in Australia, Brazil, Honduras and the U.S.

The Most Expensive Fire Opal in the World

The Fire of Australia is known as the finest uncut opal in existence and is worth $900,000 AUD, or roughly $679,000 USD.

The stunning gem is about the size of a softball and weighs 998 grams. It was found in 1946 in the Eight Mile opal field in the Australian town of Coober Pedy and remained with an opal-mining family for over 60 years.

It is now on permanent display at the South Australian Museum, where everyone can see its dazzling display of colors.

21. Poudretteite

Price per carat: $3,000

Highlights: This is an extremely rare gemstone that is usually found only in small crystals, not larger stones.

What Makes Poudretteite So Valuable

Poudretteite was first discovered as small crystals in the 1960s in Quebec, Canada. The extremely rare mineral is borosilicate, similar to quartz and cordierite, and creates barrel-shaped crystals.

Poudretteite comes in shades of violet and pink and was named after the Poudrette family, who owned the quarry where the first specimen was found. Until recently, all Poudretteite came from Canada, but in 2000, the first gem-quality stone was found in Myanmar.

Even now, transparent gem-quality stones over 1 carat are extremely rare.

The Most Expensive Poudretteite in the World

The largest and finest poudretteite currently known to exist belongs to the Smithsonian.

Discovered in a quarry in Quebec in 2006, the gem weighs 9.41 carats and is nearly flawless.

The poudretteite actually appeared on the market in 2006, where it was valued at $20,000-$30,000, then was gifted to the Smithsonian in 2007 by Frances Miller Seay.

20. Black Diamond

Price per carat: $3,000-$5,000

Highlights: Black diamonds are a rare and expensive type of fancy-color diamonds, and they’re growing in popularity.

What Makes Black Diamond So Valuable

Black diamonds are opaque fancy-color diamonds that are colored by graphite under intense heat and pressure. In the ground, they often look like pieces of charcoal, which is why they’re often called "carbanados."

Lower-quality stones, which are naturally greyish, are often heat-treated to darken and turn them into black diamonds. Gems made this way are significantly less expensive than naturally black diamonds.

Celebrities wearing black diamond jewelry are fueling the rise in popularity of this unusual stone.

The Most Expensive Black Diamond in the World

It's difficult to ascertain what the most expensive black diamond in the world really is, since the largest and most valuable ones are steeped in mystery.

One black diamond, the Spirit of de Grisogono, is believed to be 312.24 carats but was sold in a private sale, with the price realized never being publicly announced.

Then there's the Korloff Noir, an 88-carat, 57-facet diamond originally discovered in Siberia in 1917. It's billed as the world's largest known black diamond and belongs to Daniel Paillasseaur, who owns Korloff Paris. It's insured for $37 million.

19. Demantoid Garnet

Price per carat: $3,300

Highlights: Demantoid garnets are extremely rare and valuable and are usually only seen in antique jewelry.

What Makes Demantoid Garnet So Valuable

Demantoid was first discovered in 1868 in Russia’s Ural Mountains in a region that produces rare garnets. The stones come in a range of yellow, green-yellow and green shades.

Demantoid’s name means "diamond-like lustre," and the stone actually contains more brilliance than a diamond.

The stones that are mined are typically small in size, almost never over 10 carats in size, and their supply remains low despite new global sources being discovered.

The Most Expensive Demantoid in the World

Since demantoids are mined in small sizes, fewer than a few carats, there aren't huge, multimillion-dollar examples to draw from.

However, the Smithsonian has a demantoid that's 11.24 carats. Found in Russia, the emerald-green stone was discovered in the 1990s.

Its value isn't stated, but at $3,300 per carat, the gem would be worth around $37,100.

18. Black Opal

Price per carat: $3,500

Highlights: Pure black opals are very rare and only found in two places.

What Makes Black Opal So Valuable

Opals are formed when water and silicon dioxide leak into natural faults in the earth or fossils, forming a gem with sparkling colors. Black opals are rarely completely black, usually dark gray, blue, green or gray-black. Only the opal’s background is dark, and the fiery colors stand out more than in lighter opals.

Arab legends say that opals are created by trapped lightning, accounting for the sparkling effect, as the colors seem to sparkle as the stone is moved.

Black opals are found only in Australia and Nevada.

The Most Expensive Black Opal in the World

There are two Black Opals valued in the area of $1 million.

The first is known as "Halley's Comet," the largest black opal in the world, which weighs an astonishing 1,980.5 carats. It was discovered in Australia in 1986. The opal was said to have been up for sale at $1.6 million, although sale prices, if any, are elusive.

In 2013, it came back on the auction block at Bonhams, where it was listed with an estimated worth of $450,000-$650,000 but did not sell.

Another opal, known as "The Pacific," weighs 443.56 carats and is valued at around $700,000. Sale prices also have remained elusive.

17. Benitoite

Price per carat: $4,000

Highlights: Benitoite is the state gem of California.

What Makes Benitoite So Valuable

Benitoite is a blue to blue-purple gemstone made of aluminum oxide with magnesium, iron and zinc. It was first discovered in San Benito County, hence the name, and is the state gem of California.

However, the deposit is the only commercial-scale mine in California and has stopped producing, making Benitoite even harder to find. The only other country that the gem has been found in beside the U.S. is Japan.

The World's Most Expensive Benitoite

Benitoites found are generally 1 carat or smaller and don’t usually exceed 2 carats. The largest known facet-cut Benitoite stone weighs 7.7 carats and is on display at the Smithsonian Museum.

At 7.7 carats, the gemstone would be valued at around $30,800.

16. Ruby

Price per carat:$4,500

Highlights: While a gem-quality stone can be bought for about $4,500 per carat, unique rubies can sell for as much as $1 million per carat.

What Makes Ruby So Valuable

Rubies, like sapphires, are made of corundum. Rubies are colored red by chromium and are rarer than sapphires or diamonds. The word ruby comes from the Latin "ruber" or red.

Historically, these gems were owned by the rich and powerful, and many stones ended up in crown jewels or as part of aristocratic collections. Rubies were believed to inspire love, attract wealth and offer protection from misfortune, illness and injuries in battle.

Until the 1980s, most stones came from Australia, but they are now mined in many countries across Asia, Africa and Europe.

The World's Most Expensive Ruby

Most expensive ruby in the world, Sunrise Ruby

Rubies can be exceptionally expensive. One ruby, weighing 25.59 carats and set between four small, 2.4- to 2.7-carat diamonds, sold for a record 28.25 million francs, or $30.42 million at a Sotheby's auction in 2015.

It's called "Sunrise Ruby," and is described by having a crimson "pigeon's blood" hue. The previous record for a ruby was $8.6 million for a Graff ruby ring.

15. Musgravite

Price per carat: $6,000

Highlights: This is an extremely rare gem in the Taaffeite family, and until recently, only eight stones were known to exist.

What Makes Musgravite So Valuable

Musgravite, a member of the Taaffeite family of minerals, was first found in the Musgraves Ranges in South Australia in 1967, hence its name. The mineral is composed of magnesium-rich beryllium oxide.

For many years, only eight stones were known to exist. However, more recently, small deposits have been found in Greenland, Antarctica, Sri Lanka, Madagascar and Tanzania.

The first large gem-quality stone was only discovered in 1993. Musgravite is still very hard to get and top-quality gems can sell for as much as $35,000 per carat.

The Most Expensive Musgravite in the World

Musgravite is so rare that examples of them selling are difficult to come by.

There's one for sale at Gem Rock Auctions which is billing itself as the largest musgravite in the world at 16 carats. The heart-shaped stone is selling for $800,000.

14. Padparadscha Sapphire

Price per carat: $8,000

Highlights: The unusual Padparadscha is considered the world’s rarest type of sapphire.

What Makes Padparadscha Sapphire So Valuable

As we know, sapphires are made from corundum, one of the hardest substances after diamond. But instead of the typical blue color we know sapphires to be, the unusual Padparadscha is salmon pink and is considered the world’s rarest sapphire.

Padparadscha Sapphire comes from the Sanskrit word "padma raga," or pink lotus. The gem is mostly mined in Sri Lanka but also found in Vietnam, Madagascar and Tanzania.

The Most Expensive Padparadscha in the World

The most expensive padparadscha sapphire in the world sold at a Christie's auction in 2017 for 19.3 million HKD, or about $2.5 million USD.

The brilliant, pink-orange sapphire ring weighs 28.04 carats and is set in a gold with a marquise-shaped diamond two-tiered bombe.

Another extremely expensive padparadscha ring, the Du Pont padparadscha, sold for $930,000 in early 2020.

13. Red Beryl (Bixbite)

Price per carat: $10,000

Highlights: Gem-quality red beryl is so rare that rubies are 8,000 times more common, and gem-quality diamonds, 150,000 times more common.

What Makes Red Beryl So Valuable

Red Beryl, or Bixbite, was discovered in 1904 in Utah and is made up of beryllium, aluminum and silicate. The stone was named after mineralogist Maynard Bixby. Red beryl is found in hues of strawberry, ruby, cherry and sometimes orange.

The main source, and the only source of gem-quality stones, is Utah. But smaller, low-quality stones have been found in New Mexico and Mexico.

The Most Expensive Red Beryl in the World

Red Beryl has an average price per carat of $10,000, but they can be much more expensive.

For example, a "museum quality" red beryl went on the market for an estimated price of $80,000-$100,000 at Bonhams in 2014. It was "only" 2.44 carats. But to keep that in perspective, a two-carat red beryl is as rare as a 40-carat diamond.

The largest known red beryl weighs 8 carats. We're not sure how much that one's worth, but it's going to break records if it ever comes up for auction.

12. Paraiba Tourmaline

Price per carat: $10,000-$20,000

Highlights: Paraiba tourmalines were only recently discovered but are very popular, especially with jewelry designers.

What Makes Paraiba Tourmaline So Valuable

Paraiba tourmalines originate from Paraiba in Brazil, hence their name. They are a relatively new gemstone and were first discovered in 1989. The stones are known for having an "electric" color in pale blue to mint-green hues.

The darker blue stones from Brazil are the most expensive at up to $20,000 per carat. Paraiba tourmalines are also found in Africa.

However, mines are not able to keep up with production demand, and the price of this unusual stone is expected to rise in the future.

The Most Expensive Paraiba Tourmaline in the World

The most expensive paraiba tourmaline is a pair of earrings.

One weighed 7.46 carats, and the other 6.81 carats, and they sold for about $2.78 million at a Christie's auction in 2018. That equals a price of $194,730 per carat, roughly 10 times the regular price-per-carat value.

11. Alexandrite

Price per carat: $12,000

Highlights: Alexandrite is a rare stone that was once only found in Russia.

What Makes Alexandrite So Valuable

Alexandrite was first discovered in Russia in the 1830s and named for Alexander II, the Czar of Russia. Until recently, Russia was the only known source of the gem, but East Africa, Brazil and Sri Lanka all now mine Alexandrite.

The stone is known for its remarkable ability to change color from green in daylight to red in artificial light. This is due to chromium, iron and titanium in the stone and the light spectrum colors these elements absorb.

Alexandrite is sometimes referred to as an "emerald by day, ruby by night."

The Most Expensive Alexandrite in the World

The largest alexandrite in the world is an uncut, 122,400-carat stone known as the Sauer Alexandrite. It's held in Roger Sauer's private collection at Amsterdam Sauer in St. Thomas, Virgin Islands. The price on that thing is up to the imagination.

One of the most expensive alexandrites that was actually sold is an unmounted, 21.41-carat stone which realized a price of $1.325 million CHF (about $1.4 million today) at a Christie's auction in 2014.

10. Taaffeite

Price per carat: $15,000

Highlights: Taaffeite is one of the rarest gems, with only about 50 known to exist, making it a million times rarer than diamonds.

What Makes Taaffeite So Valuable

Taaffeite is made from a combination of beryllium, magnesium and aluminium. The stone is named after the man who discovered it in 1945, Count Richard Taaffe, a Bohemian-Irish gemologist.

Taaffeite ranges in color from clear to red and blue shades of purple. The mineral was formerly labeled spinel, which has a reddish color and is often confused with rubies.

Taaffe identified the new gem from a cut stone he found in a parcel of spinels. While taaffeite can sell for around $2,500 a carat, gem-quality stones sell for up to $15,000 per carat.

The Most Expensive Taaffeite in the World

The largest taaffeite in the world is a 5.36-carat gemstone owned by Miho Ozawa of Japan, according to the Guinness Book of World Records.

While this gemstone is valued up to $15,000 per carat, you might have a hard time finding that price at auction. A 5.34-carat taafeite sold for $20,000 at Bonham's in 2018, and there's one available at Heritage Auctions for $15,000.

7. Serendibite (Tie)

Price per carat: $18,000

Highlights: Serendibite is extremely rare and almost never found in gem-quality stones.

What Makes Serendibite So Valuable

Serendibite is an extremely rare mineral form of silica with boron and is dark blue-green to green-blue in color.

The mineral is named for Serendib, the old Arabic name for Sri Lanka, where the stone was first discovered.

Traditionally, Sri Lanka was the only source. However, deposits were recently discovered in Myanmar.

The Most Expensive Serendibite in the World

The largest cut Serendibite stone known belongs to the Ophir Collection, a U.S.-based lapidary firm, and it holds a Guinness World Record as the largest of its kind.

It weighs a whopping 140.76 carats, and at $18,000 per carat, it's worth around $2.5 million.

7. Clear Diamond (Tie)

Price per carat: $18,000

Highlights: Diamonds are in great demand for engagement and wedding rings, and top gem-quality stones are rarer and expensive.

What Makes Them So Valuable

Diamonds are graded, and the price is determined by the 4 Cs: cut, color, clarity and carat. Stones can vary widely in price, with top quality-gems starting at around $15,000 to $18,000 per carat.

Diamonds are usually associated with engagement or wedding rings. Engagement rings have been around since ancient Roman times and once signified a contractual agreement or an agreement of love and obedience.

After 1947, when DeBeers (the diamond mining company) launched a wildly successful ad campaign with the slogan, "A diamond is forever," diamonds became the standard engagement ring gem.

The Most Expensive Clear Diamond in the World

The most expensive clear diamond ever sold netted $33.7 million in 2017 at a Christie's auction. It weighed 163.41 carats and was set on an emerald necklace.

The most expensive clear diamond in the world is the famous Great Star of Africa, which weighs 530.2 carats and is worth at around $400 million. It is part of England's Royal Collection Trust and is on display.

The Great Star of Africa was one of nine pieces that were cut from the Cullinan Diamond, the largest uncut diamond ever found.

7. Emerald (Tie)

Price per carat: $18,000

Highlights: Emeralds are rarer than diamonds, and gem-quality emeralds are more expensive than the same quality of diamond.

What Makes Emerald So Valuable

Emeralds are made of the mineral beryl, with small amounts of chromium or vanadium, and are green to blue-green in color. Only darker-colored gems are called emeralds, while lighter ones are known as beryl. The darker the color and the larger the size, the more valuable the gemstone.

Emeralds have been prized throughout history by royalty and the wealthy. They symbolize paradise and immortality. Emeralds are found mostly in Colombia, Brazil and Zambia.

The Most Expensive Emerald in the World

The Rockefeller Emerald is the most expensive emerald ever sold by weight, selling for $5.51 million in 2017.

It weighs 18.04 carats and is set on a platinum band and flanked by small diamonds.

Then there's the Bahia Emerald, a 752-pound emerald that has been the epicenter of a decade-long legal pursuit and which might be worth $925 million.

5. Grandidierite (Tie)

Price per carat: $20,000

Highlights: Grandidierite is very rare, and only one in 1,000 stones are gem quality.

What Makes Grandidierite So Valuable

Grandidierite is a rare mineral in opaque to translucent blue-green or green-blue hues that appears as different colors when seen from different angles. It was first discovered in 1902 in Madagascar and named after the French explorer, Alfred Grandidier, who wrote about the island’s natural history and geography.

The mineral is often confused with jade. Translucent and transparent Grandidierite stones are considered gem quality, although only one in 1,000 qualify. The stone is difficult to cut and is often made into cabochons: shaped and polished rather than faceted.

The Most Expensive Grandidierite in the World

The largest grandidierite in the world belongs to the Medici Collection, and it weighs 764 carats.

If it could fetch a price of $20,000 per carat, that would make the enormous gemstone worth $15.28 million.

5. Jadeite (Tie)

Price per carat: $20,000

Highlights: Jadeite is the rarest variety of jade and highly sought-after by collectors.

What Makes Jadeite So Valuable

Jadeite is the rarest variety of jade and comes in a range of colors. Jadeite is often carved into statues, decorative objects and weapons as well as jewelry. The stone is very popular with collectors, particularly in China.

The Olmecs, Maya and Aztecs of Meso-America valued jadeite more than gold and carved ceremonial objects from the stone. The Maori of New Zealand created both weapons and traditional ornaments.

The Most Expensive Jadeite in the World

The most expensive jadeite jewelry ever sold was the Hutton-Mdivani necklace that sold for $27.44 million in 2014.

It is composed of 27 jadeite beads.

4. Painite

Price per carat: $50,000-$60,000

Highlights: Only three Painite stones were known until 2001, making it the rarest gem in the world.

What Makes Painite So Valuable

Painite is a dark red or brownish-orange red. Only three stones were known until 2001, and only a few additional specimens that can be faceted have been found since then, making this the rarest gemstone in the world.

The mineral is named after gemologist, A.C.D. Pain, who discovered it in 1957. It’s possible that there are more stones in the world, but in the past, they were misidentified as ruby or garnet.

Myanmar is the only source of Painite crystals.

The Most Expensive Painite in the World

The most expensive piece of painite in the world belongs to the Medici Collection and weighs in at 213.52 carats.

At a price of $50,000-$60,000 per carat, that would price this painite at $10.67 million to $12.8 million.

3. Blue Diamond

Price per carat: $52,000-$300,000 and up

Highlights: Found in only three mines in the world (in Australia, South Africa and India), blue diamonds are extremely rare.

What Makes Blue Diamond So Valuable

The extremely rare blue diamond gets its color from traces of the mineral boron. The shades of these fancy-color diamonds vary from green-blue, to gray-blue, to intense blue hues that range from light to dark.

The stronger and more intense the blue, and the less of a secondary color it has, mixed with the weight, determine how expensive the stone is.

The Most Expensive Blue Diamond in the World

Christies Auction House sold the Oppenheimer Blue diamond, a vivid pure blue stone, for $57.5 million in 2016.

The diamond weighed 14.62 carats and was mounted in platinum, making it one of the most expensive rings in the entire world.

2. Pink Diamond

Price per carat: Up to $700,000 (and some)

Highlights: Just 0.0001 percent of all diamonds are pink ones.

What Makes Pink Diamond So Valuable

Pink diamonds are another form of fancy-color diamonds.

Experts disagree about what gives a pink diamond its color, but the prevailing theory is that the gem’s molecular structure is actually broken down by the pressure of being formed.

Pink diamonds can have secondary hues of purple, brown or orange.

The Most Expensive Pink Diamond in the World

The Pink Star Diamond, a completely flawless gemstone, set a record in 2017 as the most expensive diamond ever sold at auction, selling for a whopping $71.2 million at a Sotheby's auction.

The vividly pink diamond weighs 59.6 carats and is mounted in platinum.

1. Red Diamond

Red Diamonds are the most expensive gemstones — The most expensive gemstone is a red diamond.

Price per carat: $1 million

Highlights: Only a small number of red diamonds have been found in just a few mines worldwide. Almost all are less than 1 carat in weight.

What Makes Red Diamond Such an Expensive Gemstone?

Red diamonds are fancy-color diamonds that are so rare that only a handful are found each year and only in a few mines worldwide. They are the most expensive type of diamond, costing more than blue or pink ones.

Again, experts disagree about what gives a red diamond its color, as they don’t contain impurities, but the prevailing theory is similar to that of the pink diamond.

The gem’s molecular structure is actually broken down by the pressure of being formed.

The Most Expensive Red Diamond Gemstone in the World

The largest known red diamond ever found, the Moussaieff Red Diamond, weighs 5.11 carats and is valued at $20 million.

It's the rarest red diamond in the world and belongs to Moussaeiff Jewellers (with two Ls), an exclusive London-based jewelry company.