Table of Contents
What is a Pearl?
A pearl is a natural gem created by a living organism. When a foreign object is introduced into a mussel or oyster, the animal coats the irritant with a substance called nacre. Layers of nacre build up to make a pearl.
Natural pearls are formed naturally by the oyster. After three or more years, a Natural pearl of good size (4-12 mm) can be found inside an oyster. Natural pearls are -sometimes- worth around 10 times more than their cultured pearl equivalent.
Due to their natural origin, natural pearls have many shapes: baroque or odd-shaped, drops, ovals, buttons and -very rarely- round.
2) Cultured Pearls
Cultured pearls are formed by the joint efforts of Man and Mollusk, as opposed to a natural pearl. Farmers implant a fine bead into the oyster where it cannot be expelled. The oyster does the rest and creates its lustrous masterpiece – the cultured pearl.
3) Imitation / Synthetic pearls
Imitation Pearls are usually a coated glass bead. Most have a high luster, but not the depth of luster seen on high quality cultured pearls. Some imitation pearls (also called shell pearls) are simply made of mother-of-pearl, coral or conch shell, while others are made from glass and are coated with a solution containing fish scales called essence d'Orient.
Internal Structure of a natural pearl and cultured pearl
Types of Cultured Pearl
Prized for their brilliant luster and rich color, Akoya pearls are a symbol of elegance and beauty. Akoyas from Japan and China are grown in pearl oysters and depending on the size of the oyster, they grow from 3-10mm.
2) South Sea
South Sea pearls are among the largest commercially harvested cultured pearls in the world. The average size of a South Sea pearl is 13 mm, with most harvests producing a range of sizes from 9 mm to 20 mm. Their color ranges from silvery white to gold. They are quite costly due to their size and rarity.
3) Tahitian Black
Exotic black pearls from the Pinctada margaritifera or Black-lip pearl oyster, are more commonly known as Tahitian pearls. They have a naturally dark body color and range from 10mm size and above, which has made them one of the most sought-after, expensive pearls in the world. Colors of Tahitian Pearl range from silvery gray and green to deep purple and black.
Mabe (pronounced Mar-bay) are known as half-pearls or blister pearls. They are the Large, hemispherical cultured pearls grown against the inside shells of oysters rather than in the oysters' bodies. Due to their half-round shape, they are most popular in earrings, rings and brooches. The size of mabe pearls varies from 12 to 20 millimetres in diameter.
Mabe cultured pearls are less expensive than round cultured pearls.
Freshwater pearls are cultivated in mussels rather than oysters, and most of the world’s supply is farmed in the lakes, rivers and ponds of China, Japan and the United States. Shapes can be freeform, rice shaped, off-round or spherical, and colors range from milky white to peach, pink and lavender. These pearls are an affordable option, often favoured by first time pearl buyers, and are available in many styles of jewellery to suit a wide variety of customers.
Also known as seed pearls, these tiny cultured pearls can be as small as a grain of sand and form accidentally in many cultured pearl oysters. Keshi pearls are a shape rather than a type of pearl as is commonly believed. They are formed when the oyster rejects and spits out the implanted nucleus before the culturing process is complete, or the implanted mantle tissue fractures and forms separate pearl sacs without nuclei. These pearl sacs eventually produce pearls without a nucleus. Keshi pearls can form in either saltwater or freshwater mollusks.
Many are curved, while some can be rock-shaped baroques. Common Sizes – 4MM to 15MM
Baroque pearls are pearls with an undefined, irregular shape. Freshwater pearls are most commonly baroque as freshwater pearls are mantle-tissue nucleated instead of bead nucleated. So the pearls are almost never round. Due to their shapes, baroque cultured pearls are often less costly than round cultured pearls.
Types of Synthetic/Imitation Pearls
1) Bathed pearl
A mother-of-pearl core coated with a mixture of plastic enamel, lead carbonate, mica, and titanium dioxide, then with a film of iridescent nylon.
2) Bohemian pearl:
Cut and buffed mother-of-pearl protuberance.
3) Glass pearl:
Glass bead dipped or sprayed with pearlescent material, or hollow glass bead filled with pearlescent material. Wax-filled pearl simulants are hollow glass beads coated with essence d'orient and filled with wax.
4) Mother-of-pearl pearl:
Crushed nacreous shell powder, sintered into the desired shape.
5) Plastic pearl:
Plastic core coated with pearlescent material.
6) Roman pearl:
Alabaster core coated with pearlescent material
7) Shell pearl (1):
Cut, buffed, and sometimes dyed nacreous portions of mollusc shells. Variations and alternate names include cat's-eye pearl, coque de perle (from nautilus shells), mother-of-pearl pearl (from mother-of-pearl), and hinge pearl (from the hinge of bivalve shells).
8) Shell pearl (2):
Spherical shell core coated with pearlescent material
Characteristics of Pearls
Each pearl harvested has its individual characteristics, making it essential to establish quality grading standards.
Luster is the amount of light a pearl reflects. The inner glow of the pearl combined with the surface brilliance. The better the nacre quality of the pearl, the more superior is its luster
Slight blemishes and little marks are part of a pearl's natural texture and proof it being genuine. These blemishes are caused by sea particles that drift into the oyster and brush against the pearl as it forms. Fewer surface imperfections denote a higher quality, more valuable pearl. For example, The gem-quality pearl may have minute blemishes when examined very closely, but they are not noticeable at arm's length.
Of the many shapes available, perfectly round pearls are the rarest and most valuable. Slightly off-round, semi-bar oque and baroque pearls are not as valuable as perfectly round pearls, however, they can be lustrous and appealing and have a natural beauty and value of their own.
Pearls vary widely in color, based on the type of oyster that produces them. The rarer the shade, the more valuable is the pearl. Whereas, the color of the pearl is really the wearer's preference.
While size does not affect the quality of cultured pearls, it does affect the price. Large pearls are more difficult to cultivate because oysters often reject the large implanted nucleus; their rarity creates higher value. Pearls are measured in diameter increments of millimeters (mm). The classic Akoya pearl generally ranges from 3mm to 10mm. South Sea pearls begin at 8mm and can grow as large as 18mm.
A Guide to Pearl Qualities and Grades
There is no international standard for grading pearls so identical pearls may be graded differently by different suppliers.
Pearls have their own jargon but most reputable pearl sellers use the two below mentioned grading system and follow accepted industry conventions.
1) A, AA, AAA grading system
2) A to D system for Tahitian Pearls and South Sea Pearls
1) A, AA, AAA grading system
< 75% clean
> 75% clean
> 95% clean
0.25 to 0.35mm
0.35 to 0.5mm
2) The A-D System ( or Tahitian System)
This grading system grades pearls on a scale from A to D, with A being the highest grade. .
Pearls of the 'D' variety may have a combination of minor and deep defects over no more than 60% of its surface. In this grade of pearl, the luster is irrelevant. Even the most lustrous pearls will be graded 'D' if their surface area is blemished to this extent.
Pearls below 'D' grade are considered not acceptable for use in jewelry.
Caring for Pearls
Pearls are delicate gems and require a little care to get the best out of them. If well taken care of using the techniques described below, the pearls will last for generations.
Before wearing, always check the prongs that support the pearls, the clasps of necklaces and bracelets and the screws of earrings. Pearl necklaces and bracelets are strung with specialized silk threads for both strength and beauty. However, if that thread stretches or is exposed to water, it may break suddenly. That is why it is strongly recommend that the pearls should be restrung every year.