Diamonds, rubies, sapphires, and emeralds are all considered to be precious gemstones, whereas most other types of gemstones (quartz, tiger’s eye, agate, etc.) are filed under the semi-precious category. The reason that diamonds, rubies, sapphires, and emeralds are so prized is largely because they are rare, whereas most semi-precious gemstones are relatively common by comparison. The rarer a gemstone is, the more expensive it tends to be.

What are the most valuable gems in the world according to both rarity and price? We all know that diamonds, rubies, sapphires and emeralds fall on the list. Let’s take a look at some particularly unique species of these stones as well as others you may not be as familiar with.

10. Blue garnet

When you picture a garnet, you probably picture a deep red stone. There are also blue garnets, but they are very rare, and can sell for $1,500 per carat. Generally these blue hues are only spotted in color-changing garnets, which may look blue or purplish red depending on the angle you hold them at. Are there true blue garnets which are always blue? Maybe, maybe not. There are rumors that they exist. If they do, they are worth even more.

9. Painite

This is another gemstone you probably have not heard of, unless perhaps you read the Guinness Book of World Records, which once described it as the rarest mineral on the planet. As a boron-based piece, painite is so rare that in 2005, there were only eighteen pieces known around the world. If you want to purchase one of these beautiful red-brown minerals, expect to pay around $1,800 per carat for the rare privilege. As it is, most of us will never see a piece of painite except in photographs.

8. Jeremejevite

This clear stone may be white, colorless, blue or yellow, and was discovered in Siberia by Pavel Vladimirovich Eremeev. They have been found throughout the world, including in Namibia, Germany, and Tajikistan, but they are very rare nonetheless, which is why they cost around $2,000 per carat.

7. Red beryl

Red is not only an uncommon color in diamonds, but also in beryl, which is generally in the blue-green hue range. Beryl is closely related to aquamarine and emerald. It is often translucent and captures the light beautifully. For this reason, red beryl is also sometimes referred to as red emerald, although this name is colloquial and not entirely accurate. How much will you pay for a piece of red beryl? Probably around $10,000 per carat.

6. Alexandrite

This is another color changing gemstone similar to the color changing garnet mentioned earlier in the list. Alexandrite is even more valuable than blue garnet, and you may pay up to $10,000 per carat for a nice piece. Alexandrite has been in increasingly high demand over the past few years, which is driving the prices higher and higher. Alexandrite typically ranges between purplish-pink and bluish-green in color. Some pieces may also range between red and blue, similar to blue garnet in appearance.

5. Serendibite

This is probably one you haven’t heard of. Nonetheless, it is very valuable, prized at around $18,000 per carat. Only two regions have ever produced serendibite, one in Sri Lanka and the other in Burma. Colors may vary, ranging from gray-blue to blue-green to pale yellow. Many pieces are also black, and may contain subtle hues or no coloration at all.

4. Grandidierite

This is one of the rarest gemstones known to exist. Like painite, there are only a finite number of known pieces. Although this gemstone is not as rare as painite (there are at least several hundred around), it may be even more expensive, valued at around $20,000 per carat. The stone is a light grayish blue in color.

3. Red diamonds

Have you ever seen a red diamond? Probably not. The majority of diamonds are white, yellow, or brown. If you find a red diamond, you probably have found the most expensive gemstone you can imagine. A nicely cut red diamond can easily sell for $20,000 per carat, and that isn’t even the upper end. Some stones may sell for substantially more. The majority of red diamonds are not a true red; they generally have a purplish tint to them. If you find a true red diamond, its value will be even greater.

2. Jadeite

Then again, it may be that jadeite is the most precious stone in the world. This type of gemstone can sell for more than $30,000 per carat. As a pyroxene mineral, jadeite may be either a bright, bold green, an emerald hue, blue, or white. Some jadeite pieces contain several different hues. The brighter the green, the more valuable the jadeite is. Note that jadeite is a type of jade, but not the most common variety. That is nephrite. If you find affordable jade on the market, it is almost certainly nephrite, not jadeite, or something else altogether such as serpentine which is used as a jade substitute. If you see really expensive jade, you are probably looking at genuine jadeite.

1. MusgraviteThis silicate mineral gemstone was first found in Musgrave, Australia, and thus the name “musgravite.” Since then, the stone has been found in Sri Lanka and Madagascar, as well as in Greenland. Musgravite is generally violet in color, usually with a grayish tint. Stones may be light or dark in color. As this stone is still incredibly rare, it may be valued at around $35,000 per carat.

Take special note that the prices which are quoted in this article are estimates only. The worth of a particular gemstone may rise or fall with popular trends as well as new discoveries in the field. Some specimens may be more valuable than others because of elements such as clarity or cut. The setting of a gemstone can also influence its value. Each of these gemstones commands a high price on the market, and every one of them has its own unique beauty. Count yourself lucky if you ever get to see one in person.