Types of Gemstones

What is a Gemstone?

Gemstones are pieces of mineral crystal that are used for decorating jewelry and other items. Certain rocks and organic materials that are not minerals are also sometimes used and are regarded as gemstones as well. These gem materials are chosen for use in jewelry manufacturing and other adornments due to their outstanding beauty, rarity, and durability. However, the faceted gems that you see in fine jewelry have usually been cut, polished, and occasionally treated to enhance their appearance. Thus, they often look very different from the natural stones that were mined.

Gemstones come in a variety of different colors. Indeed, the names of several precious gems are also used as adjectives or synonyms for a particular color. For example, emerald, turquoise, and aquamarine all refer to a particular shade of green or blue.

Gemstones also differ in terms of their physical properties and resistance to scratching, which is measured on the Mohs Scale for mineral hardness. The scale runs from 1 to 10, with 1 representing the softest mineral and 10 the hardest. While most precious stones are hard, others are too soft and fragile to be fashioned into faceted gems. Instead, these softer gemstones are sometimes displayed in museums or collected by precious stone collectors.

Given that there are so many types of gemstones to choose from, it can be challenging to decide which one is best for you. Below, we have compiled a list of gemstones with some important facts about each one to help you make an informed buyer’s decision.

Different Kinds of Gemstones

Here is a brief introduction to some of the most popular gemstones that you can add to your gem collection. For more information, you can also check out this post by our affiliate James Allen: What are Gemstones? A Complete Guide

Precious Stones

Diamonds, emeralds, sapphires, and rubies are traditionally referred to as “precious gemstones” due to their exceptional beauty, rarity, and historical significance. This classification dates back centuries and was established when these four gemstones were the most highly valued and sought after in various cultures around the world.

Diamond

Hardness: 10 (extremely hard)

The word “diamond” comes from the ancient Greek word “Adamas,” which means unbreakable or invincible. This is unsurprising, given that diamonds are renowned for their unparalleled hardness and brilliance.

Diamonds are the crystalline form of carbon found in igneous and metamorphic rocks, which are highly prized for their exceptional beauty and rarity. Often symbolizing eternal love and commitment, they are the most popular gemstones for engagement rings and many other fine jewelry pieces.

Most of the diamonds available on the market are white diamonds, which are prized for their brilliance. However, black diamonds are slowly becoming more popular. Other colored diamonds, such as yellow diamonds, also appear in gemstone jewelry from time to time, though these are extremely rare.

To learn more about diamonds, visit our Diamond Education section.

Birthstone: April

Anniversary: 10th, 60th

Emerald

Hardness: 7.5-8 (medium-very hard)

The gem of spring, emeralds symbolize rebirth. Cleopatra, the ancient Egyptian queen renowned for her exceptional beauty, was known for her affinity for these radiant green gems.

Emeralds are a type of beryl that belong to the same mineral species of colored gemstones as aquamarine. Thus, the color range for emeralds is not limited to green colors since gems that exhibit a greenish-blue hue are also considered acceptable. Color is, however, the single most important factor in evaluating emeralds, and the more intense and vibrant the color, the greater the value of the gem.

Emeralds are also one of the most unusual gemstones since they are rarely eye-clean and almost always have visible inclusions (referred to as “jardin”). The presence of these imperfections usually reduces the value of any other gem but are considered acceptable for emeralds in their polished form.

Birthstone: May

Anniversaries: 20th, 35th

Ruby

Hardness: 9 (very hard)

Referred to as the “king of gems”, rubies have been known as the gemstone for centuries. As a variety of the corundum mineral species, rubies can sell for the highest price per carat among all the other colored gemstones.

A ruby’s color ranges from red to orange-red or purplish-red. As a result, rubies are often heat-treated to intensify their color and improve clarity. They also appear a deeper red under incandescent light.

With a name stemming from the Latin word for red (“ruber”), this fiery dark-red crystal symbolizes love and passion. As a rare collector’s gem, rubies are highly valued for their unique characteristics and aesthetic appeal.

Birthstone: July

Anniversary: 15th, 40th

Sapphire

Hardness: 9 (very hard)

With a name that comes from the Greek word for blue (“sappheiros”), you may be surprised to learn that sapphires are available in a variety of rainbow colors. Besides blue, popular colors for sapphire stones include pink, yellow, and white.

Known as the gem of truth and fidelity, the blue sapphire is among the most popular gemstones for engagement rings. Princess Diana was one of the most famous wearers of a sapphire engagement ring. It’s the very same ring now worn by Catherine Middleton, Princess of Wales.

As with other popular gemstones like rubies, sapphires are often heat-treated to enhance their color and clarity.

Birthstone: September

Anniversary: 5th, 45th

Rare Gemstones and Semi-Precious Stones

All other gemstones besides diamonds, emeralds, sapphires, and rubies are traditionally categorized as “semi-precious.” This is largely because they were more abundant or less known in the major trading centers of the past.

However, some “semi-precious” stones can be more valuable than “precious” ones depending on factors like size, quality, and rarity. For instance, high-quality alexandrite or demantoid garnet can command very high prices.

Black Diamond

Hardness: 10 (extremely hard)

A black diamond is a very unique and beautiful gem variety. Bold and mysterious, black diamonds make a statement, especially when paired with white diamonds or a minimal setting.

In nature, black diamonds get their color from the presence of dark inclusions. However, most black diamonds that you see have been heat-treated. The treatment turns any dark green inclusions in the stone darker – to the point where they appear black.

Birthstone: January

Anniversary: 2nd

Amethyst

Hardness: 7 (medium hardness)

Amethyst is a stunning variety of crystalline quartz, renowned for its range of purple hues from pale lilac to deep reddish-purple. This relatively rare mineral is found in igneous and metamorphic rocks and is highly prized for its beauty and durability.

Amethyst has been a favorite in jewelry making for centuries, often featured in rings, earrings, and pendants. It was associated with sobriety in Ancient Greece and intellect during the Renaissance in Europe. St. Valentine is believed to have worn an amethyst ring engraved with the image of Cupid.

Birthstone: February

Anniversary: 6th, 17th

Citrine

Hardness: 7 (medium hardness)

Citrine is a warm, yellow-toned variety of crystalline quartz. This semi-precious gemstone is often confused with topaz since the two gemstones are both birthstones for November, just like tanzanite, turquoise, and zircon gems share the status of being birthstones for December.

A natural yellow citrine is very rare. Most citrine gems that you see are the product of heating amethyst, another variety of crystalline quartz. The color of the finished gem can range from pale yellow to orange-brown.

Among the most popular semi-precious gemstones, citrine is sometimes referred to as the “merchant’s stone” or the “money stone”, as it is believed to bring good luck and prosperity to its wearer.

Birthstone: November

Anniversary: 13th

Topaz

Hardness: 8 (very hard)

Topaz is another popular gemstone used in jewelry making. It comes in various shades of brown, yellow, green, blue, red, pink, orange, and purple. Colorless specimens are also quite common and have occasionally been mistaken for diamonds.

Blue, the most popular color for topaz, is actually one of the rarest. The blue color is the result of irradiation and heat treatment in a lab. These treatments turn colorless or pale gems into beautiful shades of blue, such as Swiss (a light blue) and London blue (a deeper blue, almost dark blue).

Birthstone: November (precious topaz), December (blue topaz)

Anniversary: 4th (blue topaz), 23rd (imperial topaz)

Garnet

Hardness: 6.5-7.5 (medium hardness)

Garnet is the January birthstone. With its deep reddish-purple hue, it is a gemstone that exudes passion, energy, and creativity. This relatively rare mineral is typically found in metamorphic rocks and is cherished for its vibrant color and durability.

Garnet has been a popular choice for jewelry throughout history, often adorning rings, earrings, and pendants.We know this because archaeologists have discovered garnets in jewelry dating back over 5,000 years. Garnet stones are also steeped in myth and were once thought to protect travelers from harm. For example, in the story of Noah’s Ark, Noah reportedly used a garnet lantern to light the way.

While red is the most well-known color, garnets actually comprise a wide variety of colored stones. Non-red varieties of these gems include green Russian demantoid (first discovered in Russia’s Ural Mountains and the rarest and most valuable of the garnet group), African tsavorite, pink and purple rhododendron, orange or reddish-brown spessartite, and hessonite.

Birthstone: January

Anniversary: 2nd

Onyx

Hardness: 7 (medium hardness)

Onyx is a banded variety of the mineral chalcedony. The ancient Romans and Greeks often used it for producing cameos and wax seals due to its ideal texture for carving.

Today, most of the onyx used in jewelry comes in several shades of black, white, or red, in which case it is called “sardonyx.” Most black-colored onyx is the result of chemical treatment, a common practice used for thousands of years. One technique that was used in ancient times, described by the Roman philosopher Pliny the Elder in the first century, included soaking the gem in sugar water. The glossy noir style of a beautiful black onyx is perfect for art deco-style designs or used to contrast white diamonds.

Anniversary: 7th

Peridot

Hardness: 6.5-7 (medium hardness)

Called the “gem of the sun” by the ancient Egyptians, peridot is one of the few gemstones to exist in only one color: green. Vivid lime green is the most desirable color for these gems, though their color ranges from yellow-green to green tinged with brown.

Peridot gems are typically formed in the heat and pressure of the earth’s mantle, but they also exist in outer space. We know this because peridot crystals have been found in pallasite meteorites. Peridot is considered a very rare mineral, and is often displayed in museums or used for scientific study.

Birthstone: August

Anniversary: 16th

Birthstones: Names of the Gemstones for Each Month

Frequently Asked Questions

What is a gemstone?

A gemstone is a mineral crystal or stone that can be cut and polished for use in jewelry or other adornments. Ancient civilizations often prized gemstones like lapis lazuli, turquoise, and aquamarine for their vibrant colors and purported health benefits, while other gemstones like red garnet were sometimes worn as talismans for protection and good luck. Nowadays, popular gemstones used in engagement rings and other jewelry include diamonds, emeralds, rubies, and sapphires.

What is the rarest gemstone on earth?

Painite is arguably the rarest gemstone on earth. Only two specimens of this extremely rare mineral existed when British gemologist Arthur Charles Davy Pain discovered it in 1951. However, approximately a thousand more have been unearthed since then.

What gemstone is the most expensive per carat?

According to Astteria, an expert in the luxury gem trade, blue diamonds are the most expensive gemstones, valued at $3.93 million per carat. Moreover, flawless samples of these gems are extremely rare, making them all the more valuable. A famous example is “The Oppenheimer Blue,” which was sold by Christie’s Geneva for around $57.5 million (which equates to approximately $3 million per carat) in 2016.

How to tell if a gemstone is real?

The only way to tell if a gemstone is genuine is to take it to a certified jeweler. They will be able to confirm the origin of the stone (i.e., whether it is natural or synthetic) and check for any cracks, scratches, and black spots that are indicators of gem quality.

Which gemstone is the hardest?

The diamond is rated the hardest gemstone on the Mohs Scale, with the only substance hard enough to cut a diamond being another diamond.

How many types of gemstones are there?

Gemstones come in a range of colors and a variety of different shapes and sizes. Approximately 200 different gemstones have been identified in the world today. Some of these precious and semi-precious stones are plentiful, while others are rare.

Which is the world’s most expensive gemstone?

The most expensive gemstone ever sold is the Pink Star Diamond, valued at $83 million.

What is a birthstone?

A birthstone is a gemstone that is symbolic of your birth period, representing either the month or astrological sign. Birthstones make excellent gifts in the form of a ring or a pendant for a necklace.

How are gemstones formed?

Gemstones are formed in various parts of the earth’s crust. Most start out as mineral deposits that begin forming crystals when they are exposed to the right amount of heat and pressure. Note that different types of gems require different levels of heat and pressure to start forming crystals. This is due to the chemical composition of the minerals that make up a gemstone.

What stones are rarer than a diamond?

The International Gem Society lists ten stones that are rarer than a diamond: Tanzanite, Burma Ruby, Jadeite, Alexandrite, Paraiba Tourmaline, Ammolite, Kashmir Sapphire, Natural Pearl, Red Beryl, and Benitoite.

Is ruby more expensive than sapphire?

Strictly speaking, rubies tend to be rarer than sapphires and are, therefore, more valuable.

Which precious stone is considered the luckiest?

Iron Pyrite (also known as Fool’s Gold) is the ultimate stone of luck, prosperity, and abundance. It is said to attract wealth by summoning the Law of Attraction.

Which is the most valuable gemstone in the world?

Listed here are the ten most valuable gemstones in the world:

Tanzanite—$1,200 per carat

Black Opal—$9,500 per carat

Red Beryl—$10,000 per carat

Musgravite—$35,000 per carat

Alexandrite—$70,000 per carat

Emerald—$305,000 per carat

Ruby—$1.18 million per carat

Pink Diamond—$1.19 million per carat

Jadeite—$3 million per carat

Blue Diamond—$3.93 million per carat

Which gemstone has the most sparkle?

A round brilliant cut diamond has the most sparkle compared to other stones, although moissanite comes in a close second.

What is the difference between crystal and gemstone?

A crystal is an object made up of atoms or ions that have been arranged in a specific order and possess a certain structure. Gems, on the other hand, are precious minerals that only occur near their source. Therefore, a crystal can be called a gem, but not vice versa.

What is the most expensive birthstone?

April has the most expensive and prestigious of all birthstones: the diamond.

Is ruby more expensive than emerald?

A fine-quality ruby is generally more expensive than most emeralds, with record prices of up to $1 million per carat. Emeralds can be purchased for between 525-1125 USD depending on the color and clarity desired – but note that several factors affect the price of a gemstone!

What are the top 10 most popular gemstones?

Diamond – The hardest substance on earth, diamonds are considered the most prestigious of all gems. They are also the most popular gemstone used in engagement rings and the best gemstones to collect.

Ruby – Known as “the king of gems,” ruby is renowned for its brilliant red hue.

Sapphire – Contrary to popular belief, sapphires come in a range of colors besides blue. These are known as fancy-color sapphires and include the popular “ruby sapphire” (pink), orange, yellow, green, and purple.

Emerald – The most desirable hues for emerald are blue-green to pure, vibrant greens with no darkness or yellowing in the stone at all – just evenly distributed colors that give off a brilliant glow when the stone has been polished to resemble glass.

Pearl – Pearls are among the most beautiful gemstones in existence, being prized for their iridescent sheen. They come in a range of colors, including white, yellow, cream, brown, black, and gray. Pearls are formed within molluscs and are highly valued for their lustre and the way they react to light, making them a popular choice in various collections.

Amethyst – Amethyst is a variety of quartz. Its color varies from light purple to nearly black. Siberian amethyst is the rarest gemstone of its type, featuring a rich purple hue.

Quartz – Quartz is a crystallized mineral composed mainly of silica. Popular gemstones that belong to the quartz variety include citrine, which comes in shades of light to dark yellow, orange, and brown; amethyst, characterized by its range of purple hues; and rose quartz, which is easily recognized by its pale pink color.

Tourmaline – Tourmalines come in a range of colors, including green, blue, and yellow. Pink tourmaline is colored by the trace element manganese, while brownish-yellow stones are called dravite, and black ones are known as schorl (a type of black geode).

Citrine – Citrine colors range from light yellow to dark orange and brown. However, high-quality citrine gems have an intense golden hue, with fiery orange flashes inside. These gems can be transparent or cloudy, depending on their origin. Another color variation prized among citrines is a deep red free of brown tints. Gems that exhibit this coloration are called Madeira Citrines since they bear a strong resemblance to the wine made from the fruit grown on the Portuguese island.

Peridot – These unique gemstones are a variety of the mineral olivine. They only come in one color, namely green, but the intensity and hue can differ for each stone. Thus, peridot gems can exhibit many different shades of green, with some appearing more yellow than others.

Note: While we strive to provide accurate pricing and sizing information, please be advised that gemstone prices are influenced by multiple factors, including market trends, availability, and individual characteristics like cut, clarity, and carat weight. The prices listed are for reference only and are subject to change without notice.