What Is Mother of Pearl? Formation, Properties, & Care

Mother of pearl, also called nacre, is an iridescent layer of material that forms the shell lining of many mollusks. Pearl oysters and abalone are both sources of this substance, which is widely used as an inlay in jewelry, furniture, and musical instruments. Mother of pearl comes in several natural colors, but is often bleached and dyed for decorative use. The dye retains the shimmering layers which make the material so sought after. Nacre is a tough and resilient material, but it is relatively soft and easily scratched.

Formation

Two substances, one mineral and the other organic, combine to create mother of pearl. Tiny hexagonal plates of aragonite, a form of calcium carbonate, are arranged in layers alternating with conchiolin, a flexible protein similar to silk that is secreted by the mollusk. Aragonite on its own is very brittle, but combined with the protein it forms a strong, flexible material that can withstand hard use.

The mollusk first of all secretes a layer of conchiolin. Aragonite crystals then form on this surface at numerous points, growing until they meet each other to form tiny plates. A further layer of protein is then deposited and so on, so that over time, many layers build up.

Properties

The resilience of mother of pearl comes from its layered structure and the contrast in properties between the mineral and organic layers. The aragonite consists if hard, brittle crystals, while the organic protein layers are a natural polymer that is flexible and resistant to fracture. The aragonite gives relative rigidity to the material and the protein counteracts the brittleness of the aragonite by preventing the spread of fractures. The result is a natural product that is tough and resilient. As of 2013, research is underway into the manufacture of synthetic nacre.

Mother of pearl has a hardness of about 3.5 on Moh’s scale. This is quite soft compared with gemstones and most metals. Although its relative softness makes it easy to work with and cut into shapes, it also means that nacre objects can be easily scratched by other items of jewelry, for example.

The iridescence that makes nacre so attractive results from the fact that the aragonite crystals have a range of thicknesses that are close to the wavelengths of visible light. Some of the light that strikes the crystalline layers will go through to the layers below, while some is reflected from the upper and the lower surfaces. Layers tend to reflect particular wavelengths, that is, colors, depending on their thickness and on the angle of the light. When viewed from different angles, different colors are reflected. Small irregularities on the surfaces make every piece of nacre unique.

Function

Mollusks create mother of pearl to protect themselves. In addition to forming part of the shell, it also insulates mollusks from bacterial infection and parasites. Another function of this substance is to reduce irritation or damage from material such as sand or grit that drifts into the shell. The particle is gradually surrounded by layers of nacre, rendering it harmless. This may result in a blister-like irregularity on the inside of the shell, or it may create the unattached, spherical structure that is much prized by humans as a pearl.

Uses

The pearly lining of mollusk shells has long been noted by people living near the ocean. Many early cultures used it extensively in jewelry and it came to be highly prized. Although not as popular as it once was, many modern cultures still appreciate its beauty and mother of pearl continues to be used in jewelry, ornaments, furniture inlays and musical instruments. Some homes integrate it into tiles and other fixtures, although it is no longer used extensively.

Like other substances found in nature, mother of pearl develops irregularities as it forms. As a result, every piece of jewelry or inlay is slightly different, a fact that can add to its appeal. Artisans may work with the unusual features of a specific piece to highlight them. These irregularities may also appear in cheaper jewelry that is not as meticulously constructed.

Nacre has been much studied by scientists interested not only in its strength and durability, but also in what it can tell them about the conditions in which it formed. The thickness and structure of the layers secreted by marine mollusks depends on the temperature and water pressure. It is therefore possible to obtain valuable information about past conditions from the study of fossilized material.

Care

Mother of pearl items should not be stored with anything that might scratch them. They should be cleaned with mild soaps and water; harsher cleaning agents may react with the aragonite, especially if they are acidic. This also applies to pearls, which have an outer coating of nacre.

Where Does Mother of Pearl Come From?

Mother of pearl comes from certain mollusks, including oysters, mussels, and abalone. Mother of pearl is a biomineral, which means that it forms by way of another organism. In this case, it is the product of secretions of a mineral blend that the mollusks make called nacre. Nacre is a material comprised of calcium carbonate and is often used synonymously with mother of pearl.

Nacre

Nacre is what creates the iridescent, oil-slick-like quality inside mollusk shells. The lustrous material isn’t just pretty; it is functional. Nacre also protects the soft tissues of the mollusk inside from debris, parasites, or damage and makes up the outer covering in round pearls.

The defense mechanism traps things in its layers as the nacre is deposited. Once stuck, more layers pile on as the process continues. The resulting layers have different results depending on the mollusk and how long the cycle continues. Mother of pearl forms due to layering, while nacre blister pearls arise attached to the inside of shells, and free pearls will form in the mantle tissues.

What Colors Are Mother of Pearl?

Thanks to the iridescent nature of mother of pearl and how the layers of nacre allow light to reflect and refract, the wide range of colors can be mesmerizing. It is likely for this reason and the apparent connection to the sea that many people find mother of pearl to have calming properties that support intuition, creativity, and acceptance. Some of the most prominent colors found in mother of pearl include:

Purples
Silvers
Bronzes
Greens
Blues
Pinks
Blacks
Bleached with muted whites and creams

What Is Mother of Pearl Worth

It used to be that mother of pearl was widely traded and used in many different applications. Jewelry with mother of pearl was typical. Seaside dwellers and beachgoers alike would collect abalone and craft it into inlay for various items. Mother of pearl was a trendy embellishment from tiles to brushes to earrings to guitar necks.

Although it has not disappeared from fashion entirely, mother of pearl is not at the peak of its popularity. As a result, you can often find mother of pearl readily on beaches. The price depends on what kind of mother of pearl you are purchasing, the weight, and the number of imperfections.

The price will also depend on whether or not your mother of pearl has been bleached. Remember that nacre comes as the iridescent, multi-colored sheen of mother of pearl. It is often bleached to a whiter or cream color to mimic the desired pearl when harvested. Mother of pearl, however, has its own natural beauty that people appreciate prior to any modifications.

How To Clean Mother of Pearl

This biomineral only has a 3.5 on Moh’s scale of mineral hardness. The scale generally runs from one being the least hard with talc and ten being the hardest with diamond. Some substances and minerals fall between the category ratings, however. The mother of pearl is classified alongside platinum and is harder than copper, silver, and gold but less tensile than steel or opal, another iridescent mineral.

Knowing mother of pearl’s hardness informs jewelers and jewelry owners how to clean it properly without doing damage. Due to its nature as a biomineral, it is easily scratched and challenging to repair. Seeking professional guidance and expert cleaning services when you are ready to spruce up your mother of pearl will help prolong its beauty.

There are several different recommendations on how to clean mother of pearl. The advice ranges from professional jewelers to mother of pearl harvesters to families who have processed mother of pearl for generations. One method even suggested soaking the pearl back in the original waters in which it was harvested and then scrubbing with the ocean foliage there. While that particular recommendation may not always be possible, some other valuable recommendations for cleaning mother of pearl include: