Ocean Gemstones

Ocean Gemstones – Treasures of the Sea

If you are a gemstone lover, you might already know where the gemstones come from. Gemstones are divided into two types: inorganic and organic. The inorganic gemstones are found from the outermost layer of earth (crust) as well as in the middle layers (mantle) of earth.

Over time the gemstones in the mantle move upward due to any number of reasons and end up in the crust. Then these gemstones are mined from the crust or through the geological process; they reach the surface where they can easily be collected.

On the other hand, organic gemstones are formed due to the remains of certain marine animals. Like the inorganic gemstones, ocean gemstones can be mined from the ocean crust or can be found washed ashore with the waves.

Which Type of Gemstones Are Found in the Ocean?

Ocean gemstones include both organic and inorganic gemstones. The inorganic gemstones that are found in the ocean include Pearls, Calcite, Aragonite, and Coral. The main ingredient in the creation of these gemstones is the remains of marine animals, mainly Mollusks and Corals.

Inorganic gemstones are created deep underground due to high pressure and temperature. Through volcanic activity, these gemstones are brought up to the ocean crust where they can be mined, or they wash ashore with waves. These gemstones include Gabbro, Diamonds, Olivine, Peridotite, Serpentine, and Cassiterite.

Ocean gemstones look very different in water than they look when shaped and polished. The reason for looking different is that they are found in a raw state like coral reefs, skeletons, or shells.

Most of the gemstones that are obtained from the ocean have comparable chemical compositions but differ only in their physical structure.

Inorganic Ocean Gemstones:

Inorganic Oceans Gemstones
Inorganic Oceans Gemstones

If we take a closer look at the ocean floor, more than 50% is made from basalt. The other components that make up the ocean floor include Peridotite and Gabbro. 

Pro Tip: Gabbro is an igneous rock that is quite popular with people who like a rock tumbling and make very beautiful tumbled gemstones.

Basalt and Gabbro both contain a green-colored mineral named Olivine. Olivine is one of the main components that make the upper mantle of the earth. It is also used in the making of  Peridot, a green gemstone that can be very expensive depending upon the size.

On the other hand, Peridotite is another gemstone and is a mix of Pyroxene and Olivine, and its name is derived from Peridot. When hot water meets with Peridotite (hydrothermal metamorphosis), Serpentine is formed. It usually forms between the ocean crust and the mantle.

At this point, the Pyroxene and Olivine are transformed into Serpentine. Due to high-temperature water close to the ocean crust, most Olivine is turned into Serpentine before it reaches the surface.

Another ocean gemstone that holds much importance is called Cassiterite which is the main source of tin. It is carried by rivers into the seas and oceans and is deposited close to the shore.

The Cassiterite can be obtained by dredging the sediments close to the shore and can be used as gemstones or be converted into tin. Cassiterite can also be found in Metamorphic and igneous rocks.

Lastly, one of the most widely known and used gemstones is Diamond. Diamonds are washed into the oceans and seas through rivers. In 2017 about 1.3 M carats of Diamonds were obtained from the Atlantic.

Ocean diamond mining is a very big industry and dredges millions of tons of material each year to extract Diamonds.

A question that is asked quite a lot is, are ocean Diamonds different from Diamonds found on land?

Yes! Ocean Diamonds are often of higher quality than the Diamonds found on land. The reason for their higher quality is the mode of transportation. Ocean Diamonds are deposited into the sea by rivers, and low-quality Diamonds are wrecked during this process.

Due to this, only Diamonds of considerable quality survive the deposition. About 90% of Diamonds found in the ocean are of gem quality as compared to land Diamonds which are about 60% gem quality.

Organic Ocean Gemstones:

The Coral gemstone is made of tiny marine animals that are known as Coral Polyps or simply Corals. These small organisms live in massive colonies under the sea. These organisms extract CaCO3 (Calcium Carbonate) from the water.

They release this chemical to make a hard and strong skeleton around them, which serves as their home. Each generation of these organisms builds on top of the old coral that results in the formation of coral reefs (not all coral form coral reefs). 

The coral serves as the home for these tiny animals and for fish and other marine animals. The hardened skeleton of coral is used in the making of Coral Gemstones. They come in many different colors that range from red, white, orange, pink, black, and blue. 

When turning coral into gemstones, keep in mind that different corals from different gemstones due to different CaCO3 used in the formation of the coral. Another thing to keep in mind is that the coral gemstones are not entirely made from Calcium Carbonate.

Calcium carbonate is either in the form of Aragonite or Calcite. Both of them have similar chemical compositions but differ only in Physical structure. For example, if we heat Aragonite to a certain temperature that it is turned into Calcite.

These minerals can be found in both marine animal skeletons as well as skeletons of coral. Each gemstone produced from them is different due to different amounts of CaCO3. Because of this, Calcite, coral, Aragonite is organic gemstones that have comparable chemical composition but are, in fact, three different gemstones.

One of the most famous organic Ocean gemstones is the pear which also contains CaCO3. Pearls have been used to make jewellery for a very long time and can be considered the sea’s hidden treasures.

Pearls are made from a type of shellfish known as the Mollusks, mainly Mussels, Clams, and oysters. Pearls are very expensive organic ocean gemstones.

Pro Tip: The pearls made with saltwater generally cost more than the ones made with freshwater.

Can you find other Valuable Minerals in the Ocean?

Yes, you can find a lot of valuable minerals in the sea other than the ocean gemstones. The main method by which minerals are transported in the sea is by the river. Rivers erode the soil and transport that soil to the ocean floor.

Like we said earlier, tin is found in the sediments transported by the river, just like that minerals like Gold are also accumulated in the sediments close to the shore. Other than Gold, it is also possible to find Titanium and Magnesium in the same sediments.

When we look at the facts, there are more valuable minerals in the sea and the ocean than on land. Then the question arises why we do not mine the ocean floor for these gemstones and miners. The answer to this question is very simple because underwater mining is very expensive and not profitable.

Are Ocean Gemstones Expensive?

Different factors make a gemstone expensive. Factors like purity, size, lustre, color, and clarity are the cause of some gemstones costing thousands while some are costing only tens of dollars.

Regardless of where the gem is found, it is bound to cost a lot if the gem has high purity and lustre. Here is a table that shows some of the most expensive as well as cheap gemstones found in the ocean.

Tumbled Calcite.1 to 5 dollars PCS 
Gabbro.3 to 10 dollarsKilogram 
Tumbled Serpentine.10 to 20 dollars PCS
Cassiterite.50 to 300 dollars.carat
Peridot.50 to 400 dollarsCarat 
Pearl.10 to 100000 dollarsPCS
Coral10 to 300000 dollars100 grams
Diamond.100 – 1000000 dollarsPCS

Calcite and Gabbro:


As you can see from the table, Calcite and Gabbro are not that expensive and are found all around the world. They can be tumbled to get a smoother and more refined look. Their raw form, as well as the tumbling, generally cost the same. 

Pro Tip: Calcite can be tumbled easily by using a rock tumbler. It is a very easy and fun hobby.

Calcite is sold in pieces; on the other hand, Gabbro is sometimes sold kilograms and generally costs a bit more than Calcite.

Tumbled Serpentine:

Tumbled Serpentine
Tumbled Serpentine

Tumbled Serpentine is also similar to Gabbro and generally costs about 10 to 20 dollars for a piece.



Cassiterite is more of a crystal than a gemstone and is slightly more expensive than the previous entries. A small piece of this crystal can be bought for about 50 to 300 dollars.



Peridot is more expensive than the last gemstones, and depending upon the color, weight, clarity, and cut, the price of this gemstone can be around 50 to 400 dollars per carat.



Pearls are very different from other gemstones. One of these reasons is that they can be cultured. Natural pearls are more expensive than cultured pearls, and even in natural pearls, saltwater pearls cost more than sweet water pearls.

Other factors in a pears cost are the surface and thickness and the surface smoothness (thickened pears are priced more). Color, shape (round), size, and lustre also play an important role in pricing a pearl.

A single strand of high-quality pearls can cost more than 100,000 dollars.



There are two types of coral: precious coral and reef coral. Precious coral is found in the deeper parts of the ocean and is used for making jewellery. The other type is the coral reef which is not used for making jewellery but serves as a home for marine life. 

When it comes to precious coral, the red-colored coral is the most expensive. With the right purity, 100 grams of red coral can be sold for around 300,000 dollars.



Diamonds are really expensive, even among gemstones. Diamonds with symmetrical cuts, colourless or closer to colourless, can be very expensive. Ocean diamonds are especially expensive because they are of better quality and about 90% of all diamonds found in oceans are close to gem quality.

The most expensive ocean diamond can cost about 1 million dollars.

Which Ocean Gemstones Are Often Mistaken as Other Gems?

Serpentine has a green color and is often mistaken for Jade and certain types of Onyx.

Gabbro is sometimes called Mystic Merlinite or Indigo Gabbro, but Indigo Gabbro is a type of Gabbro and is mined in Madagascar. And usually, when you look for Gabbro, you find Indigo Gabbro and are often mistaken for the Dendritic agate.

Peridot has a transparent green color and is often mistaken for green topaz and emerald.

Frequently Asked Questions:

Can you find platinum in the ocean?

Yes, ocean water has a large quantity of platinum dissolved in it. It can be extracted but is very time-consuming as well as expensive. About three hundred thousand tons of platinum are dissolved in ocean water and is worth about 16 trillion dollars.

Is it possible to find gemstones on the beach?

Yes, you can find gemstones on the beach. It is considered common to find semi-precious as well as precious gems washed up on the beach. These gems are carried by the waves and are washed ashore.

You can find stones like Amethysts, Serpentine, Jasper, Olivine, Flint, and some others as well. 


Gemstones have been really popular for thousands of years. They are used to make jewellery or used for decoration. Among many different gemstones, Ocean Gemstones are very expensive and have a wider variety.

From inexpensive stone to million-dollar diamonds, the seabed offers very beautiful and mesmerizing gemstones.

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