This vibrant organic material comes from the shell of the spiny oyster; polished to display brilliant shades, including red, orange and purple.

Spiny Oyster Shell Jewelry
Multi color spiny oyster shell ring.Multi color spiny oyster shell cuff.Orange spiny oyster shell. Red spiny oyster shell earrings.Colorful spiny oyster shell.

The spiny oyster, otherwise known as spondylus, is a large family of mollusks. They are sometimes also known as thorny oysters or spondylids. A bivalve mollusk, the animal is encased in a hinged shell composed of two parts. Large quills grow from their shells, providing this creature its famous moniker. Despite its name, these creatures are not true oysters and are more closely related to scallops. Of all the many varieties that are found in the seas of the world, two significant variations are found off the Pacific coast. Both are harvested for their shells for use in jewelry and lapidary purposes.

Spiny Oyster Types

Spondylus princeps possesses a striated shell. This means that lines of grooves run along the surface of the shell. Primarily, the shells are striped with fiery coral red and orange. From these shells, many imposing, curved quills grow, initially thought to be for protection. Recent evidence suggests that these spines aid the animal in camouflage. They provide anchor points for plants and animals, such as algae and sponges. A red band can be found lining the interior of its shell. They tend to be found between 15 - 50m deep in the ocean. These mollusks favor sandy areas, and may not be attached to any substrate material, such as rocks.

Spondylus calcifer is the other variety of spiny oyster found in the Pacific. This species' shell is orange and purple in color, with reddish purple banding along the edge. The spines on this bivalve are shorter, but it grows to be larger and thicker in size. Between these two types of mollusk, we find the most common colors present in jewelry. This variety is found in much more shallow water, typically 5 – 10m deep. They tend to favor rocky formations, attaching themselves to these spots.

Processing Spiny Oyster

The flesh of spiny oysters is edible, and the mollusks are harvested for both shell and meat. After cleaning, shells need to be ground down with lapidary wheels to remove the quills. Common with many kinds of gems and lapidary materials, the shell is worked when wet, and water is also introduced during the process. Wet grinding minimizes the production of dust.



In the ancient cultures that inhabited the American Southwest, Central America, and South America, the spiny oyster served many important purposes. Besides a source of nourishment, most of these cultures attributed a religious or ceremonial value to spondylus. Some cultures also used them as currency.

Food of the Gods

There are Quechua myths recorded citing that spiny oysters were used as religious offerings to deities. Debate remains as to whether this means that these gods consumed the shell of the animal or its flesh. An interesting factor to consider is that when the mollusk is out of season, it is poisonous to humans. Some experts have suggested that religious leaders would have consumed spondylus meat during these times to experience the hallucinogenic effects offered by the tainted meat.

An Eye for Detail

These bivalve mollusks possess a set of eyes that run around the edge of its shell. In the art of the Moche, these eyes are often exaggerated and feature prominently. It suggests that there was belief associated with the extraordinary power of sight the animal may have possessed. And that may have been gained by consuming it.

Make it Rain

Inca referred to spiny oyster as mullu and used the shell as an offering for rain and good harvests during the spring. The importance of this shell was so great that there was a unique role in their society based around the mollusk. This class of person was to ensure that adequate supplies of spondylus were available at all times to Inca temples.

Disclaimer: Use of any stone or mineral is not a substitute for professional medical care or treatment, and nothing herein constitutes medical advice, diagnosis, or treatment. Information provided should not be used to treat any illness, injury, medical condition, or ailment without prior consultation with a qualified health professional.



Location: Mexico

Spiny oyster shell is harvested from the Gulf of California. Otherwise known as the Sea of Cortez, this area of water exists between the Baja California Peninsula and Mexico's mainland. Its diversity of life is thought to be one of the largest known within the world.

Landscape of Mexico.

Spiny Oyster Harvest

In ancient times, Pre-Colombian peoples would harvest spondylus through free diving. A dangerous, risky method, divers would descend from a boat or raft to the necessary depth to collect spiny oysters in nets attached to ropes. These would then be hauled to the surface, where workers would clean them on the spot. First, by removing the mollusk from its attached rock with a specialized knife.

What may be surprising to learn is that modern collection of spiny oysters occurs in a very similar manner. They are still collected by diving, but with the benefit of modern practices. For instance, modern divers will make use of compressed air in their dives, allowing them to stay submerged for longer. On the other hand, many of the techniques have remained the same. Spondylus is still collected by hand and net, as they were in the past.




• Ranks 3.5 on the Mohs scale.

• Colors range from red to orange, or purple.

• Sourced from the Gulf of California, Mexico.