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You may be wondering where your gemstone was originally found. A number of organic gems are created by certain animals living in the ocean. On the other hand, most inorganic gemstones form in the Earth’s crust (the outermost layer) while a few form in the mantle (the middle layer). Some of those in the mantle move up to the crust over time.
These gemstones are either mined from the crust or they reach the surface of the Earth through geological processes. As you may have guessed, some of these gemstones are mined from the oceanic crust while others are deposited on the ocean bed or near the shore.
Organic gemstones that are found in the ocean are coral, calcite, aragonite, and pearls. They are created by animals – mainly corals and mollusks. Inorganic gemstones that can be found in oceans include diamonds, gabbro, serpentine, cassiterite, peridotite, and olivine.
Most of the stones mentioned above look very different in the ocean compared to their polished forms because many of them are found in raw states on the ocean bed or in the forms of shells and skeletons or coral reefs. Some of these gems have very similar chemical compositions (or in some cases – the exact same formula) but different physical structures.
If you are interested in checking out beautiful jewelry for women with pearls you can find them by clicking here (Amazon link).
Organic Gems in the Ocean
The gemstone coral comes from the “homes” of tiny marine animals called coral polyps (sometimes they’re just called corals). These animals live in huge colonies under the ocean and extract calcium carbonate (CaCO3) from the water.
They then secrete this chemical to create strong and hard skeletons around them that serve as “homes”. Each generation of corals builds on top of the homes of the previous generation which results in the formation of coral reefs, though not all corals are “reef builders”.
The dead, hardened skeletons of corals are used to make coral gemstones which can have a variety of colors ranging from transparent/white to red, pink, orange, violet, blue, and even black.
But it’s important to know that coral gemstones are a mix of several chemicals and not just calcium carbonate. This is important because different forms of pure CaCO3 are used for different gemstones.
Calcium carbonate is found in the ocean either in the form of calcite or aragonite. Aragonite and calcite have the same chemical composition (calcium carbonate – CaCO3) but have different physical structures. If you heat aragonite to a certain temperature you will get calcite.
These minerals are found not only in the skeletons of corals but also in many other marine animals and the gemstones they produce are completely different.
Therefore, coral, calcite, and aragonite gemstones share very similar chemical compositions but are in fact 3 separate gems.
The other type of organic gems found in the ocean are pearls (which also contain CaCO3). These gems have been used for making jewelry for thousands of years and they’re created by mollusks (a category of shellfish) – mainly oysters, clams, and mussels.
Pearls are the most expensive organic gems and their price is higher if they form in saltwater rather than freshwater.
Inorganic Gemstones in the Ocean
Over half of the ocean floor is made of basalt while the rest is made of gabbro and peridotite. Gabbro is a dark igneous rock that’s often used to make tumbled gemstones.
Gabbro, basalt, and peridotite all contain a green-ish mineral called olivine, which is one of the primary components of the Earth’s upper mantle. Olivine is used to make the green gemstone peridot, which can be quite expensive in large sizes.
Peridotite, on the other hand, contains a mix of olivine and pyroxene. It gets its name from the gemstone peridot. Serpentine forms in places where peridotite undergoes hydrothermal metamorphosis (when very hot water interacts with a rock) – usually between the mantle and the oceanic crust.
When this happens, the olivine and pyroxene transform into serpentine. That’s why olivine usually turns into serpentine before reaching the surface of the Earth.
Another important gemstone that comes from the ocean is cassiterite, which is actually the main source of tin. Tin is often carried into oceans and seas by rivers and deposits near the shores.
The sediments near the shore are dredged to extract the cassiterite which can be turned into a gemstone or be used as tin. Cassiterite is also found in igneous or metamorphic rock.
Last but not least – diamonds. Diamonds are also often washed into seas and oceans via rivers. In 2017, 1.3 million carats of diamonds were recovered from the Atlantic Ocean.
Marine diamond mining is a huge industry that dredges material from under the ocean floor then extracts the diamonds (if there are any) from the gravel.
Are marine diamonds different from land diamonds?
Yes, marine diamonds are usually of a higher quality. The reason for this is diamonds found in the ocean were transported there by rivers and this process can wreck low-quality diamonds.
As a result, only diamonds with the best quality survive and make it into the ocean. Over 90% of marine diamonds are gem quality, whereas less than 60% of land diamonds are good enough to become gems.
What Else Can You Find in the Ocean?
I talked about tin being transported into seas and oceans but this is also true for gold which sometimes accumulates in sediments close to the shores. Magnesium and titanium can also be found in these areas.
But it’s important to keep in mind that deep-sea mining is expensive and it’s often not profitable to extract these materials from the ocean.
Are Ocean Gems Expensive?
First of all, regardless of where the gem comes from, the price of a gemstone depends on numerous factors such as size, purity, luster, clarity, color, and cut. Find a summary table for typical ocean gems and their prices:
|Calcite (tumbled)||$1 – 5||pcs|
|Aragonite (tumbled)||$1 – 5||pcs|
|Gabbro||$3 – 10||kilogram|
|Serpentine (tumbled)||$10 – 20||pcs|
|Cassiterite||$50 – 300||carat|
|Peridot||$50 – 400||carat|
|Pearl||$10 – 100,000||pcs|
|Coral||$10 – 300,000||100 grams|
|Diamond||$100 – 1,000,000||pcs|
Calcite, aragonite, and gabbro are quite cheap since they are abundant all over the world. You can buy tumbled calcite or aragonite for a couple of dollars (or their crystals in raw form for the same price).
Gabbro is sometimes even sold in kilograms rather than separate pieces. Serpentine is also in a similar price range (hand-sized tumbled serpentine can be bought for under $20).
TIP: You can tumble calcite on your own, it is quite easy and you can enjoy some fun. I wrote an article on how to tumble calcite, you can read it here:
Cassiterite crystals are slightly more expensive than calcite/gabbro/serpentine but are usually not as expensive as peridot (small crystals can be bought for $50-$300).
Peridot is more expensive than calcite, aragonite, gabbro, and serpentine. Depending on its weight, cut, color, and clarity, the price of a peridot can range from $50-$400 per carat.
The value of pearls mainly depends on whether they are natural or cultured. Natural pearls are much more expensive and if they grew in saltwater – then they’re even more valuable.
The other factors that come into play are the nacre (the smooth surface – the thicker the better), the color, the size, the shape (round pearls are the best), the luster, and the surface (fewer marks and flaws make it more expensive). One strand of very high-quality pearls can be worth over $100,000.
There are 2 types of coral – reef coral, which grows in shallow water and isn’t used for making jewelry, and precious coral, which is found in deep waters and is used in the jewelry industry.
The most expensive of precious corals is red coral, but it’s not just the color that decides the prices – the purity also matters. 100 grams of high-quality red coral can sell for over $300,000.
Diamonds that have symmetrical cut, very few or no inclusions, and no color (or close to colorless) can be extremely expensive, the most expensive ocean diamonds can be worth over $1,000,000.
TIP: Diamonds are of the most valuable minerals in the world. Do you know how to recognize other valuable rocks and minerals? If you are not sure, don’t worry. Read these 6 signs to know valuable rocks and minerals:
Which of These Gems Are Mistaken for Other Gems?
Serpentine is sometimes confused with jade, verdite, and certain types of onyx.
Gabbro gemstones are often found under the names of “indigo gabbro” or “mystic merlinite” but indigo gabbro is one specific type of gabbro that’s mined in Madagascar and is relatively new.
If you search for gabbro gems you will mainly find indigo gabbro. These are sometimes mistaken for dendritic agate (merlinite).
Peridot is sometimes mistaken for emeralds or green topaz.
Coral can be confused with carnelian or rhodonite (though this is rare).
FAQ about Ocean Gemstones
Still did not find the answer to your answers about gemstones from ocean? Find frequently asked questions in the section below:
Which stones are often associated with the ocean?
Abalone (which is actually a collective name for a range of sea snails and gastropod mollusks and their shells are sometimes turned into gemstones), beach stones, ocean jasper, agate, aquamarine, amazonite, aqua aura, chrysocolla, moonstone, larimar, opal, and moonstone.
Is there platinum in the ocean?
Yes, there is a lot of platinum dissolved in seawater but extracting it would be very time-consuming and expensive. There are an estimated 300,000 tonnes of platinum in all of the oceans of the world which is worth approximately $16 trillion. But after processing this platinum you would be left with about a thousand times less platinum.
Can you find gemstones on the beach?
It’s a common occurrence to find ordinary rocks as well as semi-precious and precious gems on beaches. They can occur naturally in the area or be carried ashore by the tide. Examples of stones found on beaches include agates, amethysts, jaspers, serpentine, olivine as well as basalt, granite, quartz, flint, schist, and other rocks.
BTW: Do you want to know more about rocks and minerals identification? The books listed below are the best ones you can find on the internet (Amazon links):
- Smithsonian Handbooks: Rocks & Minerals
- Gemstone & Crystal Properties (Quick Study Home)
- Ultimate Explorer Field Guide: Rocks and Minerals (National Geographic Kids)
TIP: Find out where are the best places to dig for rocks and minerals in the US. I wrote separate articles for each state in the US. So feel free to check them out here: