Pearls: A Buying Guide to Nature’s Most Elegant Treasure

Pearls are one of nature’s most extraordinary gifts — organic gems born from the heart of mollusks and shaped by time, biology, and water. Whether formed naturally or cultivated by human hands, pearls have captivated civilizations for millennia. In this guide, we’ll explore everything you need to know to understand and appreciate these timeless treasures: from their formation and varieties to their quality factors, treatments, and cultural significance.

Whether you're a gem lover, a collector, or simply looking to create meaningful jewelry, this guide is your starting point.

Contents

1. History of the Pearl
2. Etymology
3. Origin and Formation of the Pearl
4. Ecosystem of the Organisms
5. History of the Cultured Pearls
6. Cultivation Process for the Cultured Pearls
7. Cultured Pearls
   1. Akoya Cultured Pearls
   2. Tahitian Cultured Pearls
   3. South Sea Cultured Pearls
   4. Pearls of the Sea Of Cortez
   5. Cultured Freshwater Pearls
   6. Keshi Pearls
   7. Mabe Pearls
8. Main Production Areas for Natural Pearls
9. Pearl Classifications – Quality of Pearls
10. Pearl Treatments
11. Imitation Pearls
12. Famous Pearls
13. Care and Maintenance of Pearls
14. Pearl Birthstone
15. Pearl Nomenclature (CIBJO)
16. Physical Properties of Pearls
17. Structure of Natural and Cultured Pearls
18. Pearl Units of Weight

HISTORY OF THE PEARL

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Pearls have adorned the human body for more than 4,000 years. Writings referencing pearls date back to 2500 B.C., testifying to their long-standing value and symbolism.

In India, pearls held religious significance and were worn by both men and women. Later, Alexander the Great brought pearls to ancient Greece, where they became a fashionable ornament until the fall of the Roman Empire. The fascination with pearls resurfaced during the Renaissance (15th–17th centuries), when they were again treasured for their natural elegance.

At the end of the 19th century and the beginning of the 20th, pearls experienced unprecedented demand. This led to the overexploitation of natural pearl banks, triggering a dramatic decline in their availability. Around the same time, cultured pearls began to appear on the market, marking a new era in pearl history (1910–1920).

ETYMOLOGY

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The name comes from the Greek word margaron, which means daughter of the sea, in reference to its origin.

The name “pearl” comes from the Greek word margaron, meaning “daughter of the sea,” reflecting its marine origin. In Latin, it became margarita — the root of many modern terms for pearl.

In Roman times, pearls were especially fashionable, with women often wearing elongated, pear-shaped earrings. The name evolved from margarita to perula, referring to the pearl’s shape. Eventually, it became the English word pearl.

ORIGIN AND FORMATION OF THE PEARL

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A pearl is an organic gem of animal origin. It forms as a defensive response of a mollusc (typically lamellibranch or bivalve species) to a foreign body — like a grain of sand, larva, or shell fragment — becoming lodged in its tissues.

To protect itself, the mollusc forms a depression in its mantle, enclosing the intruder in epithelial tissue. These cells then secrete nacre, which is deposited layer by layer around the foreign object, forming a pearl with a concentric structure.

Nacre consists of tabular aragonite crystals (CaCO₃) arranged in a network of conchiolin, a set of complex proteins.

Pearls grow at a rate of about 4–5 layers per day, each around 0.5 µm thick. While the active growth period spans approximately 6 months per year, it can take 30 years for a pearl to reach 10 mm — although South Sea pearls tend to grow at nearly double this rate.

ECOSYSTEM OF THE ORGANISMS

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Both natural and cultured pearls thrive in similar ecosystems:

• Temperature: Warm, clean waters between 20ºC and 25ºC

• Depth: Between 10 and 20 meters

• Survival limits: Between 10ºC and 28ºC

When water temperatures drop below 18ºC, oysters enter hibernation, limiting their productive activity to roughly half the year.

Oysters typically live 7 to 10 years, although some species can survive 30 to 40 years. However, climate change and pollution have made cultivating these organisms increasingly complex.

HISTORY OF THE CULTURED PEARLS

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Cultured pearls, as we know them today, are the result of pioneering efforts by Japanese researchers Tatsuhei Mise, Tokichi Nishikawa, and Kokichi Mikimoto.

Wikipedia

Mikimoto, in particular, devoted two decades to perfecting the technique of cultivating spherical pearls. Between 1910 and 1920, he succeeded in commercializing cultured pearls — a breakthrough that forever changed the pearl industry.

The first cultured pearls came from Pinctada martensii (Akoya oysters), which measure around 7 cm in diameter and live between 7 and 8 years.

CULTIVATION PROCESS FOR THE CULTURED PEARLS

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Cultured pearls are grown on specialized farms, where oysters are either raised from larvae or collected from the wild (as in Australia).

During the larval stage, molluscs attach to branches placed underwater. After about 3 years, the larvae reach maturity and are ready for nucleation.

Once mature, the oysters are gently opened and a spherical core — usually made of nacre from freshwater molluscs — is inserted along with a piece of epithelial tissue. The mollusc then begins coating this nucleus with nacre, forming a pearl over time.

Oysters are placed in mesh pockets suspended in the sea using chaplets, trays, or lantern baskets. They are periodically removed for cleaning and health checks. Despite intensive care, only 25–30% of the oysters will produce commercial-quality pearls. The cultivation period ranges from 9 months to 8 years, depending on the variety.

CULTURED PEARLS

(FRESHWATER AND SALTWATER CULTURED PEARLS)

There are two main categories of cultured pearls: saltwater and freshwater, each with distinct molluscs, environments, and characteristics.

AKOYA CULTURED PEARLS

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• Oysters: Pinctada fucata martensii and Pinctada fucata chemnitzii (smallest pearl-producing oysters)

• Regions: Japan, China, Vietnam, South Korea, and Australia

• Culture time: 9–16 months

• Nacre thickness: 0.35–0.7 mm

• Size: 2–11 mm (average 6–8 mm); pearls over 10 mm are very rare

• Shape: Round, near-round, and baroque

• Color: Typically white or cream bodycolor, with overtones of pink, green, or silver

• Features: Known for their great luster and symmetry, Akoya pearls are considered the classic round pearl

TAHITIAN CULTURED PEARLS

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• Oyster: Pinctada margaritifera (black-lipped oyster)

• Region: French Polynesia, around Tahiti

• Culture time: 2–3 years

• Nacre thickness: 2–6 mm

• Size: 9–17 mm (average 10 mm)

• Shape: Round, near-round, oval, button, drop, and baroque

• Color: Naturally dark, with bodycolors of green and overtones like silver, copper, and “peacock” (iridescent purple-blue)

• Note: Tahitian pearls are celebrated for their exotic hues and bold elegance

SOUTH SEA CULTURED PEARLS

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• Oyster: Pinctada maxima (silver-lipped and gold-lipped varieties, determining the pearl’s color)

• Regions: Indian and Pacific Oceans — primarily Australia, the Philippines, Indonesia, and Myanmar

• Culture time: Minimum of 2 years; can range from 3 to 8 years

• Nacre thickness: 2–6 mm

• Size: 9–20 mm (average 13 mm)

• Shape: Round, near-round, button, oval, drop, and baroque

• Color: White, silver, and golden tones, sometimes with blue or pink overtones

• Note: These pearls are known for their impressive size and thick nacre

Source: Pearl Guide

PEARLS OF THE SEA OF CORTEZ

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• Oysters: Pinctada mazatlanica and Pteria sterna

• Region: Gulf of California (Mexico)

• Culture time: 2 years for oyster growth + 2 years for pearl cultivation

• Nacre thickness: 0.8–2.3 mm

• Size: 8–14 mm (average 10 mm)

• Shape: Primarily baroque, also semi-baroque, round, and near-round

• Color: Green bodycolors with overtones of silver, purple, gray, and copper

• Note: These pearls are among the rarest and most ecologically sustainable cultured pearls

Source: Perlas Mexicanas

CULTURED FRESHWATER PEARLS

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• Regions: Primarily China, also Japan and the United States

• Molluscs: Unio and Hyriopsis genera

• Pearl count: Each mollusc can produce 4 or more pearls per valve (up to 15 insertions)

• Culture time: 2–6 years

• Size: Up to 17 mm

• Shape and color: Wide range — round, oval, baroque, button; white, pink, lavender, and more

• Note: More affordable than saltwater pearls, freshwater pearls are ideal for versatile designs

KESHI PEARLS

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• Origin: Formed spontaneously, without a nucleus, often as a byproduct of cultivation

• Occurrence: Found in both saltwater and freshwater molluscs

• Size: Typically 4–8 mm; specimens over 10 mm are rare

• Shape: Usually baroque

• Color: Wide color range; 100% nacre, resulting in strong luster and pronounced orient

• Note: Their all-nacre structure gives them exceptional brilliance

MABE PEARLS .

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• Structure: Hemispherical; formed against the mollusc’s shell rather than inside the tissue

• Process: Once harvested, the nucleus is removed and the cavity is filled with resin, then sealed with a layer of mother-of-pearl

• Use: Common in earrings, rings, and brooches

• Note: Also known as blister pearls, Mabe pearls are valued for their symmetry and large display surface

MAIN PRODUCTION AREAS FOR NATURAL PEARLS

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Natural pearls are typically found in tropical regions. However, many natural pearl-producing areas overlap with oilfield zones, and due to pollution, oyster populations have declined drastically, making natural pearl harvesting extremely rare.

Main historical sources of natural pearls:

• Persian Gulf

• Australia

• Indonesia

• India

• Sri Lanka

• The Philippines

• Malaysia

• The Red Sea

• Madagascar

• Gulf of California

• Panama

• Venezuela

Freshwater sources: Mississippi River, Scotland, Sweden, Pakistan

MAIN PRODUCTION AREAS FOR CULTURED PEARLS

Until the 1990s, Japan was the primary producer of cultured pearls. Today, China is the leading producer — especially of freshwater pearls and Akoya pearls.

Although Japan’s production has declined, it remains one of the largest distributors of cultured pearls worldwide.

Other major producers include:

• Australia, Indonesia, Philippines, and Myanmar — primarily producing South Sea pearls.

PEARL CLASSIFICATIONS – QUALITY OF PEARLS

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By Size

Larger pearls are typically more valuable. Size is directly related to the species of mollusc.

By Shape

• Round

• Near-round

• Semi-baroque (oval, button, drop)

• Baroque
  Perfect symmetry and roundness increase value.

By Color

Pearl color depends on the species and environment. Most pearls have a bodycolor and overtones.

By Luster

Luster is the most critical quality factor — it's the shine and glow that reflects light. Different types of pearls show different levels of luster.

By Nacre Thickness

The thicker the nacre, the better the pearl’s durability and luster. Nacre quality is tied to the number of layers the mollusc deposits.

Orient

The iridescent play-of-color (called orient) comes from light interference within the nacre layers.

By Surface

Pearls may show:

• Clean surfaces (no visible imperfections)

• Lightly spotted

• Moderately spotted

• Heavily spotted
  Minor imperfections are natural and testify to authenticity.

PEARL TREATMENTS

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Color Enhancements

• Bleaching: Common for Akoya and freshwater pearls

• Dyeing: Silver nitrate and other dyes used to darken nacre

• Irradiation: Alters conchiolin to darken the pearl

Surface Enhancements

• Polishing or cleaning of natural imperfections

• Heat treatments and coatings used to improve appearance

IMITATION PEARLS

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Types include:

• Solid painted glass pearls: Historical, no longer produced

• Hollow glass pearls: Coated with “essence of orient” (guanine), filled with wax

• Majorica pearls: Glass core coated in essence of orient — widely used

• Plastic and hematite pearls

• Strombus shell pearls: Simulate pink pearl tones

FAMOUS PEARLS

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• La Peregrina: Historic pearl, once owned by Elizabeth Taylor (Panama, 16th century)

• Imperial Hong Kong Pearl: Baroque, 127.5 ct

• Pearl of Asia: 240 grains, elongated shape

• Pearl of Allah: Largest known natural pearl (6.4 kg)

• Abernathy Pearl (“Little Willie”): Freshwater pearl, nearly spherical

• Arco Valley Pearl: Gift from Kublai Khan to Marco Polo (575 ct)

• Hope Pearl: 450 ct, now in the British Museum

• Other notable names: Big Pink Pearl, Gogibus Pearl, La Huerfana, La Pellegrina
  

CARE AND MAINTENANCE OF PEARLS

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Pearls are organic and delicate. Nacre can deteriorate over time if improperly stored.

• Avoid dryness and excess humidity

• Pearls are sensitive to acids, perfumes, cosmetics, and perspiration

• Store them in soft, breathable cloths

• Keep them away from other jewelry to prevent scratches

• Clean gently with mild soap and water

PEARL BIRTHSTONE

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Pearls are:

• The birthstone for June, along with Alexandrite and Moonstone

• Traditional gifts for the 3rd and 30th wedding anniversaries

• Associated with purity, stability in marriage, and emotional balance

• In Vedic astrology, pearls are linked to the Moon and its calming influence

More on Birthstones →

PEARL NOMENCLATURE (CIBJO)

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• Official classifications:

  • Natural Pearl (or simply Pearl)

  • Cultured Pearl

  • Composite Cultured Pearl

  • Imitation Pearl

  These terms are defined and standardized by CIBJO (World Jewellery Confederation).

PHYSICAL PROPERTIES OF PEARLS

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• Hardness: 2.5 to 4 (Mohs)

• Density: 2.66 to 2.78 g/cm³

• Transparency: Opaque

• Colors: White, cream, pink, gold, silver, blue, gray, near-black

• Luster: Pearly to soft matte, due to surface structure

• Orient: Iridescence caused by light diffraction within nacre

• Refractive Index: 1.530 to 1.686

• X-ray Transparency: Natural pearls appear semi-transparent

• Fluorescence: Blue or red (black pearls tend to fluoresce reddish)

• X-ray Fluorescence: Cultured pearls show signs due to the presence of manganese in the nucleus
  

STRUCTURE OF NATURAL PEARLS AND CULTURED PEARLS

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• Microstructure:

  • Natural pearls consist of layers of nacre throughout

  • Cultured pearls have a nucleus with an outer nacre coating

• Macrostructure:

  • Surface appears uneven at microscopic level

  • Only natural and cultured pearls show this feature — not imitations

PEARL UNITS OF WEIGHT

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• Carat: 1 ct = 0.20 g

• Pearl Grain: 1 grain = 0.25 ct = 0.050 g (traditional unit)

• Momme: 1 momme = 3.75 g = 18.75 ct

• Kan: 1 kan = 1000 mommes = 3.75 kg 
  

A Gem Born of Patience and Nature

More than a jewel, the pearl is a natural miracle — shaped by time, water, and life itself. No two are alike. Whether you admire their organic beauty or their centuries of symbolism, pearls have always whispered stories of the sea and elegance.

At MdMaya Gems, we celebrate that uniqueness. Our cultured pearls are carefully chosen for their luster, color, and presence, ready to become part of your most meaningful moments — or your private collection.

Let yourself be captivated by their quiet brilliance.