What Determines Gemstone Rarity?

Rarity is a valued quality for gemstones. However, few people realize just how rare a particular gem is. Advertising campaigns for jewelry are partly the reason for this because they often perpetuate the idea that a gemstone is rare even though it isn’t. As it happens, though, most gemstones are rare, with some being rarer than others.

Size and clarity also play a role in the rarity of a gemstone, including the extraction and faceting processes. We will examine each of these factors below, along with how rarity influences the price of a gem.

Gem Size and Rarity

To understand how gem size affects rarity, you first need to know where gemstones come from and how they are formed.

Most precious stones start out as elements or minerals in the earth’s mantle or crust. Then, under certain environmental conditions, these minerals develop into crystals. The crystals are essentially the rough form of the polished, faceted gems used in jewelry. The only problem is these crystals are often formed deep below the earth’s crust, making their extraction difficult.

However, sometimes crystals are brought to the surface through earth processes, such as volcanic eruptions and tectonic activity. Due to the volatile nature of these processes, large crystals are often broken up into smaller pieces, which is why small crystals are generally much easier to find than large ones. Unfortunately, these unstable and often dangerous environments also make extraction processes difficult, which, in turn, contributes to a gem’s rarity.

Gem Clarity and Rarity

Gem-quality stones are not typically found in large quantities, and flawless ones are the rarest gemstones of all. As such, many gem varieties are treated to improve their appearance in terms of color and clarity.

Whereas color describes a gem’s hue, clarity refers to the extent to which internal or external impurities are present in a transparent gemstone. Internal impurities are called inclusions, while any marks on the surface of a gemstone are called blemishes.

Clarity is always evaluated according to a particular benchmark for each gem species to account for differences in their formation processes. For example, emeralds with inclusions are generally considered acceptable in the gem trade, whereas amethyst is required to be inclusion-free.

Typically, clarity evaluations are based on the visibility of inclusions to the naked eye, including their size, number, and location. However, note that inclusions are not an inherently negative feature of a gem’s appearance. On the contrary, certain gems would not exist without them. For example, the star effect on a star sapphire is created by minute, needle-like inclusions within the gem’s crystal structure.

Thus, even though flawless gemstones are often marketed as the rarest and most desirable, gems with imperfections are sometimes even more so.

How Does Rarity Impact The Price of a Gem?

Gemstone rarity and price don’t always go hand in hand. Supply and demand play a role as well. As a result, rare gems are sometimes more affordable than gems that are more abundant simply because not many people know that they exist. Part of the reason for this is that stones that are hard to find and facet are not commonly used in jewelry and are not frequently advertised, unlike gems that are easy to mine in commercial quantities.

Diamonds are a case in point. Due to some clever advertising campaigns, colorless diamonds are thought to be the rarest gemstones. To put this into perspective, think about the fact that the vast majority of women own at least one diamond. But if diamonds are so readily available in the jewelry world, why are they so expensive? The answer is that they are always in high demand.

Of course, many other factors impact the price of a gem, such as color, clarity, and carat weight, but demand will always play the most prominent role in this regard.

Now that you are aware of the factors that determine the rarity of a gemstone let’s find out more about some of the rarest gemstones in existence.

Top Ten Rarest Gemstones (2020-2021)

1. Red diamond

As you know, diamonds are not as rare as the jewelry industry would like you to believe. However, this only applies to colorless diamonds, which exist in relatively good quantities in nature. Colored diamonds, on the other hand, are much rarer.

Red diamonds are the rarest among the different color varieties, with only an estimated 20 to 30 specimens in existence. Most of these specimens are also small – less than half a carat in size. The largest sample ever found is the Moussaieff Red, an internally flawless vivid red diamond with a carat weight of 5.11 and an estimated worth of $20 million.

2. Grandidierite


Named after the French explorer Alfred Grandidier, grandidierite is a relatively unknown type of gemstone that is seldom seen in jewelry. This is mainly due to the scarcity of this blue-green gem, which has only been found in a few locations worldwide. However, most gem-quality grandidierite comes from Madagascar.

Besides being rare, grandidierite is also quite a challenging gem to cut, making faceted pieces few and far between. The few specimens that exist are mostly cut into cabochons, which gives the material an attractive jade-like appearance.

3. Taaffeite

Taaffeite was discovered by chance when Austrian gemologist Richard Taaffe noticed that one of the spinel gems he had purchased was doubly refractive. Spinel is a different species of gemstone that exhibits many of the same qualities as taaffeite, so it is relatively easy to mistake one for the other. However, spinel is known to be singly refractive, which led Taaffe to send the unusual gem for laboratory testing. The results confirmed it was a new species, and it was named in Taaffe’s honor.

Since its discovery, a handful of taaffeite has been found in only three locations around the world, namely Sri Lanka, Burma (now Myanmar), and Tanzania.

4. Painite

Painite once held the world record for the rarest mineral on earth, with only three stones in existence after its discovery in 1957. In 2001, however, more crystals were found, which increased the number of known specimens to over a thousand. However, most of the gem material that was recovered at the time was not facetable, and painite remains a very rare gem to this day.

Painite is also only found in Myanmar.

5. Red beryl

Beryl 23651

Formerly known as bixbite and sometimes called red emerald, red beryl is a rare gemstone that has only been found in one location on earth, namely the Ruby-Violent claims of the Wah Wah Mountains in Utah. The gem is so rare that for every 150,000 diamonds, only one gem-quality red beryl is found.

In addition, most red beryl specimens tend to be small, with nearly all faceted gems weighing in at under a carat. Fortunately, a great deal of the stones that have been recovered from the Ruby-Violet claims exhibits an attractive bright red hue with slightly purplish undertones, evoking the color of the incredibly rare “Pigeon Blood” ruby.

6. Benitoite

640px Benitoite Natrolit

Benitoite is one of the better-known rare gems on this list for two reasons. Firstly, it is recognized as California’s state gem, and secondly, because of the reputation given it by the Gemological Institute of America. According to the Gemological Institute, benitoite is a rare and beautiful gemstone that will never be worth as much as the more popular gemstones like diamond and ruby due to its limited availability.

However, the few specimens that have been found and cut are often priced at up to $5,000 per carat, which is quite a bit more than some of the other rare gems.

7. Alexandrite

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Along with natural pearls, Alexandrite is the birthstone for June. This gem possesses an unusual characteristic that causes it to change color under incandescent light, earning the nickname “emerald by day, ruby by night”.

Alexandrite was first discovered in the Ural Mountains in the 1830s when Russia was still under imperial rule. The mines in Russia have since been exhausted, and most of the gems on the market today have been lab-created.

8. Padparadscha Sapphire

One of the rarest varieties of the mineral corundum, the padparadscha sapphire features a stunning color combination of orange and pink. It is also a fairly well-known gem, contributing to it being one of the most expensive rare gems on this list.

Its rarity, combined with its growing popularity, led to the development of an enhancement treatment that could make poorly colored pink sapphire stones resemble padparadscha sapphires. The treatment involves exposing pink sapphire to very high temperatures in the presence of beryllium, which produces the exquisite pinkish-orange hue that padparadscha sapphires are renowned for.

Padparadscha sapphires are found in Madagascar and Tanzania, but the finest specimens of these exceptional colored gemstones come from Sri Lanka.

9. Paraiba Tourmaline

Renowned for their highly saturated colors, Paraiba tourmalines are among the world’s most sought-after and expensive gemstones. However, they are also quite rare, with one Paraiba tourmaline mined for every 10,000 diamonds.

These gemstones come in a variety of colors, but the most prized and popular stones are the ones that exhibit an intense “electric” blue color. Paraiba tourmalines may also receive heat treatment to either lighten the color of a dark stone or change violet or purple-colored stones into blue gems.

10. Demantoid Garnet

Demantoid Garnet

Demantoid garnet is a rare green variety of andradite garnet that was first mistaken for emerald upon its discovery in the Ural Mountains in the 1800s.

It was an extremely popular stone during the late Victorian era and early twentieth century, during which it was sold for high prices because it was never found in large quantities. Nowadays, demantoid garnet is only available in antique jewelry pieces since no new stones have been obtained through mining.

The prices for demantoid garnet also vary considerably today, depending on the size and quality of the gemstone.

What Are The Popular So-Called “Rare” Gems?

While many popular gemstones are often marketed as rare, the fact that they are widely available in jewelry settings makes it evident that they are not as scarce as they seem. Here is a list with some more information on these so-called “rare” gems:

1. Diamond

Esther Tuttle 0u Dxovbs2e Unsplash

Contrary to popular belief, diamond is not the rarest gemstone on earth. Many other gems are rarer than diamonds, with the list above being a case in point.

That being said, flawless diamonds are exceptionally rare, in addition to the colored varieties. Rare colors for diamond include red, pink, and blue, while yellow and brown are more frequently encountered in nature.

Diamond is also one of the most precious gem materials known to man, being coveted for its hardness and brilliance. All things considered, it’s no small wonder why diamonds are and continue to be the most popular gemstone for engagement rings and other fine jewelry.

2. Ruby

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Rubies belong to the same mineral corundum as sapphire. They are a popular gemstone for their fine color, which ranges from vivid red to purplish or orangy-red.

Now corundum is a relatively abundant mineral that is mined extensively for abrasives. Gem-quality rubies, on the other hand, are quite a bit rarer, comprising only about 1% of all corundum. Of these rubies, it is estimated that less than 1% remain untreated.

Most rubies are heat-treated to improve their color and clarity, which reduces their value considerably. While heat-treated rubies below one carat are fairly common, good quality rubies larger than this are few and far between. So, while there is no shortage of small gems, a one-carat ruby is significantly rarer than, for example, a diamond of the same size.

Certain varieties of ruby are also rarer and more valuable than others. For instance, Burmese rubies mined from the Mogok Stone Tract mine in Myanmar (formerly Burma) are perceived as the highest quality gems and therefore command the highest prices.

As it turns out, the finest ruby in the world is a Burmese ruby known as the Sunrise Ruby. In addition, this impressive specimen also happens to be a Pigeon Blood ruby. The name “Pigeon Blood” refers to a rare color variation that exhibits a deep red color with a slightly purplish tinge.

The ruby’s rarity, combined with its high demand, means that these rich red gems may be an exception when it comes to rare popular gemstones.

3. Sapphire

Gary Yost Uvhy 5a4ou Unsplash

While ruby is the name given to red corundum, sapphire is the variety that most people associate with a deep blue gem. However, sapphire stones also come in various other colors, with some being quite a bit rarer than the blue ones. Pink sapphires and the pinkish-orange variety known as padparadscha are a case in point.

But, even though these rare varieties can fetch high prices in the gem trade, the demand for the blue gems is what generally determines the pricing for sapphires.


To summarize, not all gems marketed as rare in the jewelry industry are actually that. However, this is not to say that popular gems are in abundance either. In fact, gemstones as a whole are a rare occurrence in nature, with the crystallized minerals we consider gem materials making up only a tiny percentage of the earth’s substance.

Frequently Asked Questions About Gem Rarity

Which gem is the rarest on earth?

The Guinness Book of World Records named painite the world’s rarest gemstone in 2005, but over a thousand new fragments have been recovered since then. Thus, musgravite (a member of the taaffeite mineral variety) is the rarest gemstone, with only eight known specimens in existence.

What are the rarest gemstones in the world?

There are well over 200 types of gemstones used in jewelry, with many being considerably rarer than the most popular gems. Here is a list of ten of the rarest gems on earth (2020-2021):

  1. Red diamond
  2. Grandidierite
  3. Taaffeite
  4. Painite
  5. Red beryl
  6. Benitoite
  7. Alexandrite
  8. Padparadscha sapphire
  9. Paraiba tourmaline
  10. Demantoid garnet
Which birthstones are the rarest?

The rarest birthstones are:

Red diamond – April

Red Beryl – October/November

Tanzanite – December

Black opal – October

Alexandrite – June

Are rubies rarer than diamonds?

Rubies are considerably rarer than diamonds. As a result, they also tend to be more valuable, depending on their origin, quality, and size. A one-carat ruby, for example, can often fetch a higher price than a diamond of the same weight simply because they are both sought-after and scarce.

Which ruby is the most valuable?

Burmese ruby from Myanmar (formerly Burma) is the most valuable variety, along with the exceptionally rare Pigeon Blood ruby, which is the name given to a particular color variation.

Is sapphire rarer than a diamond?

Sapphires are rarer than diamonds but not as rare as rubies.


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