10 of the World’s Rarest Gemstones

There are roughly 200 varieties of natural gemstone known in the world today. Alongside the world’s precious gems (diamond, ruby, sapphire, and emerald) are numerous semi-precious stones, some of which are so incredibly rare that their value outstrips many of the world's most valuable precious gems. Here are a few of the rarest from around the world.

1. TANZANITE // FOUND ONLY IN TANZANIA

 
Tanzanite is a beautiful blue variety of the mineral zoisite, and is so named because it is only found in a small area near the foot of Mount Kilimanjaro in Tanzania. The stone was not discovered in commercial quantities until the 1960s and since then its popularity has grown tremendously, thanks largely to the efforts of Tiffany & Co. Heat-treating tanzanite at very high temperatures can improve the blue coloration, so most gems on the market have been treated in this way, but any tanzanite that has not been heat-treated and has a strong blue color naturally will be of a much higher value. Because it is only found in one small location, the value of tanzanite looks likely to soar over time; once those mines have been emptied there will be no new stones coming onto the market—unless a new source is found.

2. BLACK OPAL // THE DARKER THE BETTER

Daniel Mekis via Wikimedia Commons // CC BY-SA 3.0

 
Opals are usually a creamy-white color and are made special by the rainbow-colored inclusions that reflect the light as the stone is moved. Black opals are much rarer, because almost all of them are found in mines in the Lightning Ridge area of New South Wales in Australia. The darker their background color and brighter the inclusions, the more valuable the stone. One of the most valuable black opals of all time is the "Aurora Australis," which was uncovered in Lightning Ridge in 1938. The 180-carat opal is especially admired due to its large size and intense harlequin coloration; in 2005 it was valued at AUS $1,000,000, or about $763,000 U.S.

3. LARIMAR // ONLY FOUND IN THE DOMINICAN REPUBLIC

Wikimedia Commons // Public domain

 
Larimar is a very rare blue variety of the mineral pectolite and is found in only one small area of the Dominican Republic. This turquoise stone’s name was created by the man who brought the stone to prominence in 1974, Miguel Méndez—he took the first part of his daughter’s name, Larissa, and combined it with the Spanish word for sea, mar, to create the portmanteau larimar. Locals had known of the existence of the stone for generations, because small examples had washed up on the seashore, but it was not until the 1970s that sufficient quantities were found in the ground to open a mine.

4. PARAIBA TOURMALINE // NEON LUSTER

DonGuennie (G-Empire The World Of Gems) via Wikimedia Commons // CC BY-SA 4.0

 
Tourmalines are common in many colors across Brazil, but the Paraiba tourmalines are the only stones with a bright turquoise hue, thanks to their copper content. The very rare gems were discovered in 1987 by determined miner Heitor Dimas Barbosa, who had been driven by a belief that something special lurked under the hills of the Brazilian state of Paraiba. Barbosa was right, and after years of fruitless digging, he finally unearthed a tourmaline of unrivaled neon blue that set the gem market alight. The extremely rare stone (only one stone is mined for every 10,000 diamonds) then became intensely sought-after. In 2003 very similar turquoise-colored tourmalines were found at mines in the mountains of Nigeria and Mozambique, although some say they are not quite as striking as the Paraiba tourmaline.

5. GRANDIDERITE // ONE EXCEPTIONAL EXAMPLE

DonGuennie (G-Empire The World Of Gems) via Wikimedia Commons // CC BY-SA 3.0

 
Grandiderite was first described in 1902 by French mineralogist Alfred Lacroix, who found it in Madagascar and named it in honor of the French explorer Alfred Grandidier, an expert on Madagascan natural history. This extremely rare blue-green mineral has been found in a number of places around the world, but so far only Madagascar and Sri Lanka have produced any gem-quality stones, and these are still extremely scant. The majority of the known stones are translucent, but the most rare, and therefore most valuable, example ever found was transparent. In fact, the stone was initially assumed to be another rare gem, serendibite, because grandiderite of that color and transparency had yet to be seen. The gem was only identified as grandiderite after expert analysis and was subsequently sold for an undisclosed sum. It’s safe to assume that if a gem of similar quality were to be unearthed, its scarcity alone would ensure it fetched an extremely high price.

6. ALEXANDRITE // COLOR-SHIFTING GEM

 
The amazing color-changing stone alexandrite was discovered in 1830 in the Ural Mountains in Russia and named after Russian tsar Alexander II. A variety of chrysoberyl, the stone’s remarkable color-shifting capability makes it especially sought-after: In sunlight the stone looks blue-green, but under incandescent light it becomes red-purple. The degree of color change varies from stone to stone, with some only showing marginal change, but the most valuable are clear stones that demonstrate complete color change.

Although some large examples of the stone have been found (the Smithsonian houses the world’s largest known cut sample of alexandrite at 65.08 carats), the majority are under one carat. This means that the value of a gem under a carat may only be $15,000, but a stone larger than one carat might fetch as much as $70,000 per carat.

7. BENITOITE // STATE GEM OF CALIFORNIA

Pablo Alberto Salguero Quiles via Wikimedia // CC BY-SA 3.0

 
Benitoite is only mined in one small area of California, near the San Benito River (hence the name), but the mine closed for commercial mining in 2006, making this gemstone yet more scarce. The gem was first identified around 1907 by geologist George Louderback and has a deep-blue color that shows especially interesting qualities when caught under UV light, when it glows fluorescent. The gem was named the official state gemstone of California in 1985 in recognition of the fact that, despite it being found in trace quantities in Arkansas as well as Japan and Australia, California is the only place where it can feasibly be mined. Due to the rarity of discovering a good quality benitoite of a reasonable size, it can fetch huge prices on the open market—a well-cut benitoite stone at over 2 carats can fetch more than $10,000 a carat.

8. PAINITE // ONCE THE WORLD’S RAREST GEM

Rob Lavinsky via Wikimedia // CC BY-SA 3.0

 
Painite was first discovered by British gemologist Arthur Charles Davy Pain in 1951 and recognized as a new mineral in 1957. For many years only one specimen of the dark red crystal was in existence, housed at the British Museum in London, making it the world’s rarest gemstone. Later on other specimens were discovered, although by 2004 there were still fewer than two dozen known painite gems. However, in recent years a couple of mines in Myanmar have begun to produce some painite, and there are now said to be over 1000 stones known. The scarcity of this gem has made it extremely valuable and just one carat can fetch more than $60,000.

9. RED BERYL // TINY AND SCARCE

Didier Descouens via Wikimedia Commons // CC BY-SA 3.0

 
Red beryl, also known as bixbite or red emerald, is so rare it is estimated by the Utah Geological Survey that a single such gem is uncovered for every 150,000 gem-quality diamonds. Pure beryl is colorless and only gains its bright hues from impurities in the rock: chromium and vanadium give beryl a green color resulting in an emerald; iron provides a blue or yellow tint creating aquamarine and golden beryl; and manganese adds the deep-red color to create red beryl. Red beryl is only found in Utah, New Mexico, and Mexico, and the majority of examples found are just a few millimeters in length, too small to be cut and faceted for use. Those that have been cut are generally less than a carat in weight, and a red beryl of 2 or 3 carats would be considered exceptional.

10. TAAFFEITE // DISCOVERED BY CHANCE

DonGuennie (G-Empire The World Of Gems) via Wikimedia Commons // CC BY-SA 3.0

 
Austrian-Irish gemologist Count Edward Charles Richard Taaffe bought a box of cut stones from a jeweler in Dublin in the 1940s, thinking he had purchased a collection of spinels. But on closer inspection, he noted that one of the pale mauve gems was not reacting to the light in the same way as the rest of the spinels, so he sent it off to be analyzed. The results revealed that he had discovered a hitherto unknown gemstone—a serendipitous but frustrating situation, since he had discovered a cut gem and had no idea where the mineral naturally occurred. Fortunately, once the new stone had been announced, many other collectors re-examined their own spinel collections and a number of other samples were uncovered. Finally the source of the stone was tracked down to Sri Lanka, although a handful have also been found in Tanzania and China. It is thought that less than 50 examples of taaffeite exist—many of which are housed in geological and private collections, making this gemstone so rare the ordinary public are unlikely to ever encounter it.

10 Fascinating Facts About the Thesaurus for National Thesaurus Day

iStock.com/LeitnerR
iStock.com/LeitnerR

Writers often turn to a thesaurus to diversify their vocabulary and add nuance to their prose. But looking up synonyms and antonyms in a thesaurus can help anyone—writer or not—find the most vivid, incisive words to communicate thoughts and ideas. Since January 18 is Thesaurus Day, we’re celebrating with these 10 fascinating facts about your thesaurus.

1. Its name comes from the Greek word for treasure.

Greek lettering.
iStock

Most logophiles consider the thesaurus to be a treasure trove of diction, but the word thesaurus really does mean "treasure." It derives from the Greek word thésauros, which means a storehouse of precious items, or a treasure.

2. You can call them thesauruses or thesauri.

Row of old books lined up.
iStock

How do you refer to more than one octopus? People say everything from octopuses to octopi to octopodes. Similarly, many people have trouble figuring out the correct plural form of the word thesaurus. Though thesauri is technically correct—it attaches a Latin suffix to the Latin word thēsaurus—both thesauri and thesauruses are commonly used and accepted today.

3. Early thesauruses were really dictionaries.

Close-up of the term 'ideal' in a thesaurus.
iStock

Ask a French scholar in the 16th century to see his thesaurus, and he'd gladly give you a copy of his dictionary. In the early 1530s, a French printer named Robert Estienne published Thesaurus Linguae Latinae, a comprehensive Latin dictionary listing words that appeared in Latin texts throughout an enormous span of history. And in 1572, Estienne's son Henri published Thesaurus Linguae Graecae, a dictionary of Greek words. Although the Estiennes's books were called thesauruses, they were really dictionaries comprised of alphabetical listings of words with their definitions.

4. A Greek historian wrote the first book of synonyms.

Stacks of books surrounding an open book and a pair of glasses.
iStock

Philo of Byblos, a Greek historian and grammarian, wrote On Synonyms, a dictionary of synonyms that scholars consider to be the first ancient thesaurus. Dating to the late 1st century or early 2nd century CE, the book lists Greek words that are similar in meaning to each another. Sadly, we don’t know much more about On Synonyms because copies of the work haven’t survived over the centuries.

5. An early Sanskrit thesaurus was written in the form of a poem.

Sanskrit lettering.
iStock

In the 4th century CE, an Indian poet and grammarian named Amara Sinha wrote The Amarakosha, a thesaurus of Sanskrit words. Rather than compile a boring list of similar words, Amara Sinha turned his thesaurus into a long poem. Divided into three sections—words relating to the divine, the earth, and everyday life—The Amarakosha contains verses so readers could memorize words easily. This thesaurus is the oldest book of its kind that still exists.

6. A British doctor wrote the first modern thesaurus.

Portrait of Peter Mark Roget.
Thomas Pettigrew, Wikimedia Commons // Public Domain

Peter Mark Roget is the British doctor credited with authoring the first modern thesaurus. In 1805, he began compiling a list of words, arranged by their meaning and grouped according to theme. After retiring from his work as a physician in 1852, Roget published his Thesaurus of English words and phrases; so classified and arranged as to facilitate the expression of ideas and assist in literary composition. Today, Roget’s Thesaurus is still commercially successful and widely used. In fact, we celebrate Thesaurus Day on January 18 because Roget was born on this day in 1779.

7. The thesaurus has a surprising link to a mathematical tool.

Image of a vintage log log slide rule.
Joe Haupt, Flickr // CC BY-SA 2.0

The division between "words people" and "numbers people" is deep-seated. Many mathematicians may try to steer clear of thesauruses, and bibliophiles may avoid calculators, but the thesaurus is actually linked to a mathematical tool. Around 1815, Roget invented the log-log slide rule, a ruler-like device that allows users to easily calculate the roots and exponents of numbers. So while the inventor of the thesaurus was compiling words for his tome, he was also hard at work on the log-log slide rule. A true jack-of-all-trades.

8. The Oxford English Dictionary has its own historical thesaurus.

Synonyms for
iStock

In 1965, a professor of English Language at Glasgow University suggested that scholars should create a historical thesaurus based on entries in the Oxford English Dictionary. The project was a massive undertaking, as people from multiple countries worked for 44 years to compile and classify words. Published in 2009, the Historical Thesaurus to the Oxford English Dictionary contains 800,000 words organized by theme and date. The thesaurus covers words and synonyms from Old English to the present day and lets readers discover when certain words were coined and how long they were commonly used.

9. One artist turned his love of words into a series of thesaurus paintings.

Mel Bochner,
Mel Bochner, "Crazy," 2004. Francesca Castelli, Flickr // CC BY-NC-ND 2.0

In 2014, the Jewish Museum in New York showed a survey of conceptual artist Mel Bochner’s art. Bochner had incorporated words and synonyms in his paintings for years—which were collectively referred to as the thesaurus paintings—featuring word paintings and lists of synonyms on canvas. The brightly colored paintings feature different groups of English and Yiddish synonyms. According to Bochner, Vietnam and Iraq war veterans cried after seeing his thesaurus painting Die, which features words and phrases such as expire, perish, succumb, drop dead, croak, go belly up, pull the plug, and kick the bucket.

10. There's an urban thesaurus for all your slang synonym needs

Copy of an Urban Dictionary book.
Effie Yang, Flickr // CC BY-NC-ND 2.0

Urban Dictionary helps people decipher the latest slang terms, but where should you go when you need a thesaurus of slang? Urban Thesaurus, of course. The site, which is not affiliated with Urban Dictionary, indexes millions of slang terms culled from slang dictionaries, then calculates usage correlations between the terms. Typing in the word money, for example, gives you an eclectic list of synonyms including scrilla, cheddar, mulah, coin, and bling.

This story originally ran in 2017.

10 Endangered Alphabets You Should See Before It's Too Late

The Glagolitic script carved into wood
The Glagolitic script carved into wood
Courtesy of Tim Brookes

The Arabic and Simplified Chinese scripts aren't in danger of going anywhere anytime soon, but the same can't be said for Balinese, Mali, Pahawh (or Pahauh) Hmong, and the other 100-some alphabets that Vermont-based writer Tim Brookes has cataloged in his online Atlas of Endangered Alphabets, which is set for a soft launch on January 17. The featured alphabets—which Brookes has loosely defined to include writing systems of all sorts—are vanishing for varied reasons, including government policies, war, persecution, cultural assimilation, and globalization.

“The world is becoming much more dependent on global communications and those global communications take place in a relatively small number of writing systems—really something between 15 and 20,” Brookes tells Mental Floss. “And because that’s the case, all the others are to some degree being eroded.”

The atlas will include a bit of background information about each alphabet as well as links to any organizations attempting to revive them. By creating a hub for these alphabets, Brookes hopes to connect people who want to preserve their language and culture, while also showing the world how beautiful and intricate some of these scripts—including the 10 below—can be.

1. Cherokee

Although the Manataka American Indian Council says an ancient Cherokee writing system may have existed at one point but was lost to history, Cherokee was more or less a spoken language up until the early 19th century. Around 1809, a Cherokee man named Sequoyah started working on an 86-character writing system known as a syllabary, in which the symbols represent syllables. Most remarkably, Sequoyah himself had never learned how to read. At the time, many Native Americans deeply distrusted writing systems, and Sequoyah was put on trial for witchcraft after tribal leaders caught wind of his new creation. However, once they realized that written Cherokee could be used to preserve their language and culture, they asked Sequoyah to start teaching the syllabary. “The Cherokee achieved 90 percent literacy more rapidly than any other people in history that we know of,” Brookes says. “[Sequoyah’s syllabary] is one of the greatest intellectual achievements of all time.”

After a period of decline in the years following the Indian Removal Act of 1830, Cherokee language education saw somewhat of a revival in the late 20th century. The predominance of English and the Latin alphabet has made these efforts an uphill battle, though. Brookes says it’s difficult to find people who can teach the script, and even among Cherokee translators, few are confident in their grasp of the writing system.

2. Inuktitut

A stop sign containing the Inuktitut script
A stop sign in Nunavut, Canada
Sébastien Lapointe, Wikimedia Commons // CC BY-SA 3.0

Nine different writing systems are used among Canada’s 59,500 Inuit. Many of these are based on the Latin alphabet, but the one shown above uses syllabics that were first introduced by European missionaries in the 19th century. Since it’s difficult and costly to represent each of these writing systems in official documents, many Inuit officials write and hold meetings in English, all but ensuring the demise of their mother tongue. However, Canada’s national Inuit organization, the Inuit Tapiriit Kanatami, is now in the process of developing one common script for all Inuit. “Our current writing systems were introduced through the process of colonization,” the organization writes on its website. “The unified Inuktut [the collective name for Inuit languages] writing system will be the first writing system created by Inuit for Inuit in Canada.” It remains to be seen what that script will look like.

3. Glagolitic

A tablet containing the Glagolitic script
The Baška tablet, which was made around the year 1100
Neoneo13, Wikimedia Commons // Public domain

It’s widely believed that Glagolitic, the oldest known Slavic script, was invented by missionaries Saint Cyril and Saint Methodius around 860 CE in an effort to translate the Gospels and convert the Slavs to Christianity. The name Glagolitic stems from the Old Church Slavonic word glagolati, meaning to speak. Some of the symbols were lifted from Greek, Armenian, and Georgian, while others were entirely new inventions. Nowadays, academics are typically the only ones who can decipher the script, but some cultural institutions have made efforts to preserve its legacy. In 2018, the National and University Library in Zagreb launched an online portal containing digitized versions of Glagolitic texts. In addition to being a source of Croatian heritage and pride, the alphabet has also become an object of tourist fascination. Visitors can view monuments containing Glagolitic symbols along the Baška Glagolitic Path on the Croatian island of Krk. And in Zagreb, the capital city, it’s not hard to find gift shops selling merchandise adorned with Glagolitic writing. However helpful this may be to the tourism sector, it's no guarantee that more Croatians will want to start learning the script.

4. Mandombe

The Mandombe script
Moyogo, Wikimedia Commons // Public domain

This African script is unusual for several reasons. For one, the Mandombe alphabet reportedly came to David Wabeladio Payi—a member of the Kimbanguist church in the Democratic Republic of Congo—in a series of dreams and spiritual encounters in the late ‘70s. One day, he was looking at his wall when he noticed that the mortar between the bricks seemed to form two numbers: five and two. He believed these were divine clues, so he set out to create a series of symbols based off those shapes. Eventually, he assigned the symbols phonographic meaning and turned it into an alphabet that could be used by speakers of the Kikongo and Lingala languages. Perhaps most remarkably, the pronunciation changes depending on how the symbols are rotated. “It’s one of about three writing systems in the world where that’s true,” Brookes says. Unlike most of the other alphabets on this list, Mandombe is growing in popularity rather than declining. However, because it’s primarily being taught in Kimbanguist schools and used only for religious texts, it will be a challenge to convince the rest of the population to start using it. Elsewhere in the country, the Latin alphabet is used (French is the official language). “What it’s up against is, in essence, exactly the same forces that a declining script is up against,” Brookes says. For this reason, many new alphabets can be considered endangered.

5. Ditema tsa Dinoko

In a similar vein, Ditema tsa Dinoko is also a minority script, and it's too new to tell if it will stick around. A team of South African linguists, designers, and software programmers invented this intricate, triangular-shaped alphabet in just the last decade in hopes of forging a single script that could be used by speakers of indigenous languages in South Africa, Botswana, Zimbabwe, and Mozambique. Because the symbols were inspired by artworks and beadwork designs that are typical of the region, the alphabet is also a celebration of culture. “One of the really interesting features of African alphabets is how deeply embedded they are in what we would call graphic design,” Brookes says. “Instead of imitating the shapes or structures or layout of other writing systems, such as our alphabet, they often start from a completely different point of view and draw on designs that are found in war paintings, weaving textiles, pottery, and all of those other available graphic elements.” The colors used in the alphabet aren't necessary to understand the script, but they hark back to the alphabet's artistic origins while also functioning as a kind of font. For instance, different writers may use different colors to give their text "a certain feel or emotional resonance," Brookes says.

6. Mandaic

The Mandaic script
Courtesy of Tim Brookes

This ancient, mystic script dates back to the 2nd century CE and is still being used by some Mandaeans in Iraq and Iran. According to mythology, the language itself predates humanity, and the script was historically used to create religious texts. Charles Häberl, now an associate professor of Middle Eastern languages and literatures at Rutgers University, wrote in a 2006 paper that Mandaic is “unlike any other script found in the modern Middle East." And unlike most scripts, it has changed very little over the centuries. Despite its enduring quality, many of the speakers in Iraq have fled to other countries since the U.S. invasion in 2003. As these speakers assimilate into new cultures, it becomes more challenging to maintain their linguistic traditions.

7. Lanna

The Lanna script
Courtesy of Tim Brookes

According to Brookes, the Lanna script was primarily used during the time of the Lanna Kingdom in present-day Thailand from the 13th century to the 16th century. It’s still used in some regions of northern Thailand, but faces stiff competition from the predominant Thai script. The word Lanna translates to "land of a million rice fields." The script is one of Brookes’s personal favorites as far aesthetics are concerned. “It is so extraordinarily fluid and beautiful,” he says. “They developed this script to indicate not only consonants, but then the consonants have vowel markings and other consonant markings and tonal markings both above and below the main letters, and so you have this amazingly joyous and elaborate writing system, and it’s like a pond of goldfish. Everything is just curving around and swimming in all these different directions.”

8. Dongba

The Dongba script
Courtesy of Aubrey Wang

Members of the Naxi ethnic minority in China’s Yunnan province have been using this colorful pictographic script for well over 1000 years. The pictures stand for tangible objects like mud, mountains, and high alpine meadows, as well as intangible concepts such as humanity and religion [PDF]. Historically, it was mainly used by priests to help them remember their ceremonial rites, and the word Dongba means "wise man." However, the script has undergone something of a revival in recent years, having been promoted by people working in the arts and tourism industries. It’s also taught in some elementary schools, and it remains one of the few pictographic scripts that’s still in use today. At the same time, Brookes says he's seen little evidence of efforts "to create a circumstance where the script is actually used in a functional, everyday fashion." With the predominant Chinese script looming large throughout much of the country, Dongba's days may be numbered.

9. Tibetan

A student writes the Tibetan script
China Photos/Getty Images

Some of the world’s alphabets and languages are endangered for political reasons. Tibetan is perhaps the best-known example of that. The Chinese government has cracked down on language instruction in recent years, with the aim of promoting Mandarin, the predominant language—although some have argued this policy comes at the expense of minority languages. In Tibet, many schools now conduct the bulk of their lessons in Mandarin, and Tibetan might be taught in a separate language course. Chinese officials put a Tibetan activist on trial in January 2018 for “inciting separatism”—partly because he criticized the government’s policies on Tibetan language education. He was sentenced to five years in prison. In general, “the story behind endangered alphabets is almost never a pleasant or cheerful one, so that’s the human rights side of it,” Brookes says.

10. Mongolian

The Mongolian script

Anand.orkhon, Wikimedia Commons // CC BY-SA 4.0

Some have likened the appearance of the traditional Mongolian script to a kind of vertical Arabic. The script traveled to Mongolia by way of a Turkic ethnic group called the Uighurs in the 1100s. Beginning with Genghis Khan, Mongol leaders used the script to record historic events during their reign. Later, when Mongolia became a Soviet satellite state, the country started using the Cyrillic alphabet in the 1940s, and the traditional script was largely cast aside. The traditional alphabet is still used in inner Mongolia and is returning to Mongolia, and the renaissance of Mongolian calligraphy has bolstered its usage to some degree. Nonetheless, it, too, remains endangered.

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