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You may be wondering where your gemstone was originally found. Several 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 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.
The Organic gemstones in the ocean are coral, calcite, aragonite, and pearls. Animals – mainly corals and mollusks, create them. 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 than their polished forms because many are found in raw states on the ocean bed or in the forms of shells, skeletons, or coral reefs. Some of these gems have very similar chemical compositions (or, in some cases, the same formula) but different physical structures.
If you want to check 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, 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 with various 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, 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 in the skeletons of corals and 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 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; their price is higher if they are formed in salt water 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.
On the other hand, Peridotite 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 from the ocean is cassiterite, the main tin source. Rivers and deposits near the shores often carry tin into oceans and seas.
The sediments near the shore are dredged to extract the cassiterite, which can be turned into a gemstone or 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 and 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. This is because diamonds found in the ocean were transported there by rivers, which 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.
TIP: Hunting for rocks at the seaside is a pleasurable pastime, and many treasures can be found. Check out how to clean rocks from the beach in the article below:
Cleaning Rocks From the Beach: 7 Ways How to Do It Properly
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 near the shores. Magnesium and titanium can also be found in these areas.
But it’s important to remember that deep-sea mining is expensive, and extracting these materials from the ocean is often not profitable.
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:
| Ocean Gem | Price | Amount |
|---|---|---|
| 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 worldwide. 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 in 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 independently; it is quite easy, and you can enjoy fun. I wrote an article on how to tumble calcite; you can read it here:
Can You Tumble Calcite? Be Careful and Follow These Tips!
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; if they grow in saltwater, 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 with symmetrical cuts, 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 one of the most valuable minerals in the world. Do you know how to recognize other valuable rocks and minerals? Read these 6 signs to know valuable rocks and minerals:
6 Signs That a Rock Is Valuable + Examples & Location Tips
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 “indigo gabbro” or “mystic merlinite,” but indigo gabbro is one specific type of gabbro 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).
BTW: Do you want to know more about rock and mineral 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)
FAQ about Ocean Gemstones
Still did not find the answer to your answers about gemstones from the 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, a lot of platinum is dissolved in seawater, but extracting it would be very time-consuming and expensive. An estimated 300,000 tonnes of platinum is in the world’s oceans, 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 common to find ordinary rocks and 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, and olivine, as well as basalt, granite, quartz, flint, schist, and other rocks.
TIP: One of the most enjoyable ways to rockhound is to stroll along the coast, looking for interesting beach rocks. Find out the most common beach rocks in the article below:
25 Most Common Rocks on the Beach: How & Where to Find Them?