Pearl Properties and Characteristics

Last updated on June 2, 2023

The pearl, one of the three birthstones for June, along with alexandrite and moonstone, comes in a large variety of colours. Although the most familiar pearl colours are white, cream and black, this beautiful gemstone’s colour palette extends to many different hues.

Pearl Origin and Formation

Pearls are exquisite organic gemstones formed within the soft tissue of shelled molluscs, such as mussels and oysters.

The name “pearl” derives from the Latin word “perna,” meaning leg, believed to be inspired by the ham-leg shape of these bivalve molluscs. It is fascinating to note that the scientific name for the family of oysters that produce pearls is Margaritiferidae, originating from the Old Persian word for pearl. Additionally, this word serves as the etymological root for the English name “Margaret.”

The highest quality natural pearls have been cherished for centuries, adorning jewellery and captivating with their inherent beauty. Among them, the Umm Al Quwain Pearl holds the distinction of being the oldest recorded reference, estimated to be approximately 7,500 years old. Unearthed from a grave in the UAE, it stands as a testament to the enduring allure of pearls throughout human history.

The formation of pearls occurs as concentric layers develop around a microscopic irritant, resulting in the luminous gem we admire. These layers comprise nacre, a remarkable substance composed of calcium carbonate (aragonite) and conchiolin, a complex protein responsible for mollusc shell formation.

Before the advent of pearl cultivation techniques, pearls were sourced from diverse regions, including the Persian Gulf, Sri Lankan waters, and freshwater locations in Europe and China. Subsequently, pearls were discovered in South America. As natural pearls grew increasingly scarce in the early 20th century, innovative methods for pearl cultivation emerged, originating in China and Japan and eventually spreading worldwide.

Natural pearls, often referred to as wild pearls, possess an air of rarity, commanding high prices due to their limited availability and petite sizes. Today, natural sea pearls can be found in various locales, spanning Japan, Central and South America, Australia, the Persian Gulf, the Gulf of Manaar, Madagascar, Myanmar (Burma), the Philippines, and the South Pacific Islands. In addition, natural river pearls can be discovered in Asia, Europe, and North America.

Cultured saltwater pearls are cultivated in regions like Indonesia, the Philippines, Australia, China, Japan, French Polynesia, and the South Pacific Islands. Similarly, cultured freshwater pearls originate from China and Japan, showcasing the ingenuity and artistry involved in pearl cultivation.

Pearl Quality Factors

Pearls are extraordinary gemstones that possess unique characteristics. Unlike other gemstones, they require no cutting or polishing and can be plucked fully formed from their shells. However, several quality factors contribute to the overall value of pearls, including nacre quality, lustre, surface quality, colour, size, shape, and matching.

Nacre Quality

The quality of pearl nacre is one of the most crucial factors in determining its value. The thickness of the nacre layer significantly influences the gem’s beauty and durability. Thin nacre allows the nucleus to be visible, resulting in a lacklustre and chalky appearance. Pearls with thick, well-layered nacre are more attractive and have greater longevity.

Lustre

Lustre, closely linked to nacre quality, is perhaps the most important value factor for pearls. It refers to the inner glow that emanates from the gemstone. Lustre is created as light enters the pearl and reflects through its layers of nacre.

Lustre measures the brightness and shine of a pearl, defining its unique beauty. The higher the lustre, the more valuable the pearl. The quality of lustre depends on the evenness and smoothness of the nacre layers and is graded on the following scale:

• Excellent: Bright and sharp reflections
• Very Good: Bright and nearly sharp reflections
• Good: Bright reflections with slight haziness around the edges
• Fair: Weak and blurred reflections
• Poor: Dim and diffused reflections

Surface Quality

Surface quality assesses the cleanliness, smoothness, and absence of blemishes on a pearl’s surface. Like other gemstones, pearls rarely achieve perfection.

The type and visibility of surface imperfections determine the pearl’s appearance and potential impact on its durability. Examples include abrasions, which are scratches or scuffs that affect lustre and colour, and bumps that resemble tiny bubbles on the surface. Wrinkles, on the other hand, indicate areas where the nacre is not smooth.

Colour

Pearls exhibit a wide range of colours and shades, including white, cream, pink, silver, golden, blue, grey, green, bronze, and black.

The colour of a pearl is influenced by the oyster’s lip colour and pigments within conchiolin, an organic substance that binds aragonite. Additionally, the thickness of the nacre contributes to the variety of shades. Thicker nacre produces more vivid colours.

Pearl colour consists of three main components: body colour, overtone, and orient. Body colour represents the gem’s dominant overall colour, while overtone refers to one or more translucent secondary colours overlaying the body colour. Orient represents a shimmer of iridescent rainbow colours. It is worth noting that all pearls exhibit body colour, but only some display overtone or orient, or both.

The value of certain pearl colours is determined by supply and demand. Pearls with more visible and saturated colours are highly sought after. For instance, white South Sea pearls with a fine pink overtone are rarer and more expensive than those with a silver overtone.

Size

In general, larger pearls are rarer and more valuable, assuming other factors remain constant. Cultured pearls can range in size from tiny 1.00mm beads to as large as 21.0mm.

The price of pearls increases with each millimetre in size due to their scarcity and the longer cultivation time required for larger specimens.

Shape

The ideal pearl shape is perfectly round, making it the rarest and most valuable among cultured pearls. However, well-formed pear, oval, and irregularly shaped (baroque) cultured pearls are also highly prized by collectors.

Regardless of the shape, an even and symmetrical form is of utmost importance when assessing the quality of a pearl.

Matching

Matching is a quality factor applied to jewellery featuring two or more pearls. It evaluates how well the pearls in necklaces, earrings, bracelets, and sets complement each other. Pearl matching considers the main quality factors, including size, shape, nacre quality, surface quality, lustre, body colour, and overtone. While body colour, overtone, pearl shapes, and sizes can be mixed to achieve unique design effects, other quality factors should be matched for a harmonious overall appearance.

Pearl Care and Cleaning

Pearls are a relatively soft organic gemstone, ranking 2.5 to 4.5 on the Mohs hardness scale, which means they require special care. They can be easily damaged by accidental impacts, harsh chemicals, and even substances found in perfume.

To protect your pearl jewellery, it is important to remove it before engaging in household cleaning. Chemicals such as ammonia, alcohol, and acids can be harmful to pearls. Additionally, substances like makeup, hairspray, perfume, and body creams can alter the colour and dull the lustre of pearls. Therefore, it is best to put on your pearl jewellery as the final step in your grooming routine.

After each wear, it is highly recommended to gently wipe your pearls with a clean, soft cloth. This practice helps prevent the accumulation of oils and dirt.

For cleaning pearls at home, use a mild dishwashing soap mixed with mineral or distilled water. Tap water often contains chlorine, which can harm pearls. Avoid soaking the pearls in the cleaning solution; instead, dip a cloth into it and gently wipe the gems. Then, use a clean, damp cloth to rinse off any residual soap and dry the jewellery with a soft, lint-free cloth. It is important to avoid using brushes, ultrasonic cleaners, or steam cleaners, as they can damage the delicate nacre of pearls.

When storing pearl jewellery, keep them separate from other gemstones to prevent scratches. It is also recommended to store pearls in a well-ventilated space, allowing for proper air circulation. Remember to periodically wear your pearls, as leaving them in storage for extended periods can result in dehydration and loss of lustre.

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