Top 20 most expensive and rarest gemstones in the world

Gemstones are made up of a variety of minerals, rocks, and organic materials. With more than 300 gemstones currently documented and more than 2000 minerals, there are bound to be some that are much rarer and more precious than diamonds, here is the list below. Substitutions of atoms in the crystal lattices, impurities, assemblies, pressure, and temperature conditions can create some of the rarest gemstones in the world. In the list below, we offer a selection of the rarest gemstones. Minerals can be classified into gemstones based on their chemical composition, refraction, crystal structure, and optical characteristics. The classification and degree of imperfections in a mineral or stone can determine the value and associated rarity.

21. Tanzanite – €1,037 per carat

Unlike most gemstones that are mined from different deposits around the world, this relatively new stone has only been found in northern Tanzania. The first gemstone was discovered by a Masai Ali Juuyawatu tribesman in 1967. Tanzanite is a blue-colored variety of zoisite. Experts predict that the supply of tanzanite could run out within the next 20-30 years, making this stone significantly rarer than diamonds.  Buying tip: Tanzanite ranks 6-7 on the Mohs scale of hardness, so it's strong enough for everyday use. The most prized color is a pure blue almost indistinguishable from blue sapphire. Most tanzanites owe their color intensity to heat treatment. To maximize color potential, look for stones of 5 carats and above. Average price per carat: €1,037 ( $1,200) for high quality stones.

20. Jeremejevite – €1,729 per carat

Jeremejevite (Al6B5O15(F,OH)3) is an aluminum-bearing borate mineral with associated fluoride and hydroxide. It was first found in the Adun-Chilon Mountains in Siberia in 1883. This gem has a hardness similar to quartz, 6.5 to 7.5 on the Mohs scale, and is therefore ideal for jewelry making. Average price per carat: €1,729 ( $2,000)

19. Fire Opal – € 1,987 per carat

Fire Opal (SiO2 nH2O) is not technically a mineral but rather a mineraloid. The reason for opal is that it does not have a crystal structure required for all minerals. As stated in the chemical formula, opal is a hydrated form of silica or silicon dioxide. Opals can form in a variety of different colors depending on the environmental conditions during formation. The opal's mineralogy allows it to diffract light, it shimmers in different colors. Average price per carat: €1,987 ( $2,300)

18. Poudretteite– $ 2,593 per carat

Poudretteite (KNa2B3Si12O30) was discovered at Mont Saint-Hilaire in Quebec in the 1960s by the Poudretteite family. The gem is naturally pink in color and has a Mohs hardness of 5. It was not until 2000 that the first gem-quality Poudretteite was found in Mogok, Burma with a weight of 9.41 carats. Average price per carat: €2,593 ( $3,000)

17. Demantoid Garnet – € 2,851

Demantoid garnet is a remarkable green variety of andradite garnet that was discovered in the mid-1800s in Russia. Although other types of warm-toned garnet are considered common and inexpensive, demantoid garnet is one of the rarest and most valuable in this family. You will be hard-pressed to find demantoid garnet over 2 carats as most crystals are smaller. Buying Tip: Demantoid Garnet falls between 6.5 and 7.5 on the Mohs scale of hardness, so the stone is perfect for everyday use with proper care. Since this variety of garnet is rarely found in larger sizes, you should look for a stone between .5 and .75 carats. Average price per carat: €2,851 ($3,300) for high-quality natural stones.

16. Black Opal – $ 3,024 for quality stones

Black opal is generally the rarest and most popular type of opal and is also considered one of the rarest of all gemstones. The world's black opal supply comes predominantly from Lightning Ridge, New South Wales, Australia. Buying advice: The main characteristic that will differentiate black opal from common opal is its body tone. Although black opals can appear in many colors, their overall composition is on the darker end of the spectrum. Be sure to buy black opal from a reputable dealer. Average price per carat: €3,024 ($3,500)

15. Benitoite – €3,458 per carat

Benitoite (BaTiSi3O9) is a brilliant blue g-stone composed of barium, titanium, and silica. Benitoite forms during the last cooling stage of hydrothermally altered serpentinite. This rare gemstone is found in San Benito County, California, hence its name. Benitoite fluoresces strongly and glows with a bright blue color. Most everyday jewelry enthusiasts will never be able to see the true beauty of benitoite. This stone was discovered in the early 1900s by George D. Louderback. It is the official gemstone of California in 1985. The stone was misidentified as spinel in the past but was eventually re-examined and reclassified due to the gemstone's high level of brilliance. Buying tip: You will need to be suspicious and find a reliable contact to buy benitoite. Stones that are too dark will not reflect light well, and stones that are too light will look washed out. Don't expect to find stones over 3 carats. Average price per carat: €3,458 ( $4,000) per carat for stones with medium blue tones.

14. Sapphire €3,458 – €5,188 per carat

Sapphire is one of the most famous gemstones. The best-known sapphire deposits are located in India, Vietnam, Russia, Thailand, Australia, the United States, China, Myanmar, Sri Lanka, and Madagascar. Blue in color, the stone can also be pink, green, or yellow-orange. Average price per carat: €3,458 – 5,188 ($ 4,000 – $6,000) per carat for stones with medium blue tones

13. Musgravite – €5,188 per carat

Musgravite is an aluminum oxide with varying proportions of magnesium, iron, and zinc. Musgravite (Be(Mg,Fe,Zn)2Al6O12) was originally discovered in 1967 at Musgrave Ranges, Australia. Other Musgravite deposits are found in Tanzania, Greenland, Madagascar, and Antarctica. Musgravites can be green, blue, or purple. This very rare and hard gemstone is in the same family as taaffeite. Average price per carat: €5,188 ( $6,000) per carat

12. Padparadscha Sapphire – € 6,919 per carat

Padparadscha (pronounced pad-pah-raj-ah) sapphires are extremely rare and are found primarily in Sri Lanka as well as Tanzania and Madagascar. It is the unique combination of pink and orange hues that make this stone one of the most sought after by collectors. Buying Tip: Padparadscha sapphires are so rare and expensive that you should opt for a stone with less clarity and a duller color or choose a stone that is smaller in size. Shapes can often be unusual and varied because cutters try to maximize carat weight. This is largely due to the rarity and demand factor for this stone. Don't expect to find these sapphires over 2 carats without paying the price. Average price per carat: € 6,919 (or $8,000) per carat for high-quality gems.

11. Red Beryl – € 8,640 per carat

Red beryl (Be3Al2Si6O18) is a mineral composed of beryllium, aluminum, and silicate. In nature, pure beryl is colorless but acquires its coloring from traces of additional elements. Red beryl occurs in mineralized rhyolite tuffs. Red beryl is an extremely rare variety of beryl that has only been found in Utah and New Mexico. It was discovered by Maynard Bixby in 1904. Although it has been found in two locations, gem-quality red beryl has only been mined in Utah. Described by some as the red emerald, this rare mineral is very difficult to find due to the unique conditions necessary for the formation of this stone. Purchase advice: Please note that synthetic red beryl has been produced. Like emeralds, red beryls often contain inclusions, but they don't necessarily impact the overall value of the gemstone. If you come across a high-quality red beryl stone with excellent clarity and a lot of carat weight, you are probably dealing with a synthetic. Large specimens of red beryl are so rare that they often remain uncut and sold to collectors as specimens. Most cut red beryl stones weigh less than 1 carat. Average price per carat: € 8,640 ($10,000) per carat for high-quality material.

10. Alexandrite – € 10,379 per carat

Alexandrite (BeAl2O4) is a type of chrysoberyl that has been found in the Ural Mountains. The difference between alexandrite and chrysoberyl is the presence of iron, titanium, and chromium present as impurities in alexandrite. Alexandrite is green in sunlight and red in incandescent light, making it one of the few color-changing gemstones on the market. The stone was discovered in 1830 in the Ural Mountains of Russia, which is also home to other unusual minerals. The stone was named after Tsar Alexander II. Buying tip: Smaller varieties of alexandrite have been mined in Sri Lanka, Brazil, and Asia, but alexandrite specimens are still very rare and expensive. Average price per carat: € 10,379 ($12,000) per carat

9. Ruby – € 12,961 per carat

Ruby is one of the most popular stones in the world, it is known for its shades of red. Its red color is due to the presence of chromium oxide, it belongs to the corundum family. Sapphires are other variants of corundum. Ruby has a hardness of 9 on the Mohs scale. the diamond has a hardness of 10. It can be found on all continents except Antarctica. The main deposits are in Thailand, Myanmar and Sri Lanka, but the most valuable Rubies come from Asia. Average price per carat: € 12,961 ($15,000) per carat

8. Diamond – € 12,961 per carat

The diamond (C) is the one we've all heard of and is the centerpiece of most engagement rings. As indicated in their chemical composition, diamonds are made of pure carbon which explains their incredible strength and durability. Diamonds are found in cooled kimberlites that have formed over 1 to 3 billion years. Average price per carat: € 12,961 ($15,000) per carat

7. Serendibite – € 15,571 per carat

Serendibite ((Ca,Na)2(Mg,Fe2+)3(Al,Fe3+)3) is an extremely rare gemstone and mineral originally discovered in Sri Lanka in 1902. This inosilicate has a complex chemical formula with many side branches of calcium, boron, aluminum, magnesium, etc. Serendibite was recently discovered in the Mogok region of Myanmar. Average price per carat: € 15,571 ($18,000) per carat

6. Jadeite – € 17,295 per carat

Although in appearance, jadeite ranks at the top of our list as one of the most valuable gemstones in the world. This gemstone is the most expensive and beautiful variety of jade. Since this dark green translucent gem is significantly rarer than other jade types, it is worth much more. Buying tip: If you want jadeite, but can't afford the price, consider buying a cheaper version, nephrite or dupe jade, aventurine. The value of jadeite is based on the level of transparency and depth of color. Some very beautiful pieces have even been sold for more than 1 million dollars per carat. Most jadeites on the market will sell for significantly less. Average price per carat: € 17,295 ($20,000) per carat for high-grade material.

5. Grandidierite – € 1,7295 per carat

Grandidierite ((Mg, Fe2+) Al3 (BO3) (SiO4) O2) is a very rare gem that can fetch up to $20,000 per carat and be first discovered in Madagascar in 1902. It is often found as an accessory mineral on boron- and aluminum-rich rocks with a pearly semi-transparent bluish-green hue. Average price per carat: € 17,295 ($20,000) per carat for high-grade material.

4. Taaffeite – € 30,249 per carat

Taaffeite (BeMgAl4O8) is a very rare mineral and is often confused with spinel. Amazingly, the gemstone was first discovered already cut and polished in Dublin Ireland in 1945. At the time the gemstone was mislabeled as spinel and upon inspection, it was determined that the mineral was actually a new unidentified gem. The main difference between spinel and taaffeite is the double refraction found in taaffeite. The gem is found in alluvial deposits in Sri Lanka and Tanzania. Average price per carat: € 30,249 ($35,000) per carat for high-grade material.

3. Blue Garnet – € 1,296,060 per carat

Blue Garnet is a very rare and extremely expensive gemstone. There are only a few deposits in Madagascar, the United States, Turkey, and Russia. Blue Garnet appears blue-green when exposed to daylight, while it turns purple when illuminated by unnatural light. The price of one carat is estimated at 1.5 million dollars. The most expensive blue garnet stone of 4.2 carats was sold in 2003, for the sum of 6.8 million dollars. Average price per carat: €1,296,060 ($1,500,000) per carat

2. Red diamond 864,790 – € 1,727,940 per carat

Above we featured the diamond as one of the most expensive gemstones, and at number 2 with a price tag of over $1-2 million per carat, we find the red diamond. There are less than 30 red diamonds found worldwide, most of them less than half a carat. You might assume that the red color comes from impurity, but it's actually derived from the plastic deformation of the crystal lattice. There is only one deposit for this stone, it is located in Australia and is called The Argyle Mine. The famous Moussaieff red diamond of 5.11ct was acquired in 2011 for 8 million dollars. It is the largest red diamond discovered in the world. Average price per carat: € 864,790 – € 1,727,940 ($1,000,000 – $2,000,000) per carat

1. Blue diamond – 3,390,000 euros per carat

The most expensive gemstones in the world are blue diamonds. Not only are they rare, but they are also known to have a spectacular shine. Of all the other gemstones, they are arguably the most popular among people. The Oppenheimer Blue Diamond is the largest vivid blue diamond ever to be auctioned. It was sold for 57.5 million dollars for a weight of 14.62 carats, or 3.39 million euros per carat.