Lesson24: Pearl Value Evaluation

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Pearl Prices

• Pearl prices reflect their quality and fluctuate based on market supply and demand. Traditionally, pearls of the same size and color are more expensive if they are saltwater pearls rather than freshwater.
  • Quality Perspective: Saltwater pearls have better luster and are more often round. Freshwater pearls typically have weaker luster, lower roundness, and may lose their sheen (turn yellow or dull) over time.
  • Supply and Demand: Saltwater pearls are produced at a lower yield (one pearl per oyster), and key production regions (e.g., Japan, Australia) enforce strict quality controls. In contrast, freshwater pearls have higher yields (up to ten pearls per mollusk), but quality varies greatly, and high-quality pearls are rare.
• Certification also impacts price. Certification costs (time, fees) and the authority of the certifying body significantly affect pricing. For example, True Pearl Research Certification (真科研) adds considerable value due to its high fees and credibility.
• Advances in freshwater pearl cultivation have improved roundness, luster, size, and color. Pearls like freshwater Akoya, Edison, and bead-nucleated pearls now rival saltwater pearls such as Akoya and South Sea pearls, driving up their prices. This improvement has established an objective grading system for high-quality freshwater pearls.
• Pearl Price Ranking:
  1. Saltwater Pearls > Freshwater Pearls
  2. Saltwater Pearls: Australian White > South Sea Gold = Tahitian > Akoya
  3. Freshwater Pearls: Edison > Bead-Nucleated = Aurora Freshwater = Non-Nucleated

Pearl Value Evaluation Criteria

I. Overview

Unlike diamonds, which have a standardized global grading system (4Cs: color, clarity, carat, and cut), pearls lack a unified system. However, common evaluation criteria include shape, nacre, blemishes, luster, color, size, and matching quality.

II. Shape

1. Types of Pearl Shapes: Pearls come in various shapes, including round, semi-round (Mabe), oval, button, circled, ringed, drop, and baroque. Round pearls are the most highly valued. Symmetrical teardrop-shaped pearls are rare and valued similarly to round pearls.
2. Distinguishing Round and Near-Round Pearls: To distinguish round from near-round pearls, place the pearl on a flat surface and gently roll it. If it rolls straight and smooth, it is round.

III. Nacre

1. Overview
   Nacre is the layer of material covering the pearl’s surface, giving pearls their unique color and rich, lustrous sheen. Nacre thickness is closely tied to durability and is a key quality indicator. Generally, the longer a pearl is cultivated, the thicker the nacre. Thickness varies by mollusk species; for instance, Akoya pearls typically have thinner nacre compared to White South Sea and Tahitian pearls.
2. Evaluation Standards
   There are no global standards, but some regions have strict nacre thickness requirements. For example, Tahitian pearls once required a minimum nacre thickness of 0.8mm on one side. This regulation ended in 2017 due to pressure from farmers. Note that thick nacre alone does not guarantee quality; pearls with thin nacre are prone to durability issues and are considered lower quality.
3. Identification Methods
   Several methods are used to assess nacre thickness:
   • Luster Observation: High-quality pearls have strong, mirror-like luster. Dull or grayish tones indicate thin nacre.
   • Surface Inspection: Look for cracks, peeling, or abrasions exposing the nucleus.
   • Translucent Test: Rotate the pearl under a light source. Visible wood-like lines suggest thin nacre.
   • Drilled Hole Inspection: Examine drilled holes for color variation between layers.
   • Professional Testing: Use X-ray or ultrasound equipment for precise measurements. Ultrasound measures the time difference between sound waves reflected off the pearl’s surface and nucleus.

IV. Flaws

1. Overview: There’s a saying, “No flaw, no pearl.” Pearls formed in natural environments typically contain flaws, and flawless pearls are incredibly rare. Some flaws demonstrate the pearl’s natural growth process and uniqueness. However, in the market, pearls with fewer flaws are more valuable.
2. Types of Flaws: Flaws are categorized into two types: natural flaws and flaws caused during processing. Here are common types of pearl flaws and their causes:
   • a. Natural Flaws:
     • Growth Lines: The most common flaw type, appearing as fine, irregular lines on the pearl’s surface, similar to tree rings. These lines result from the continuous secretion of nacre during growth. Almost all pearls have these lines, but their visibility varies.
     • Spiral Rings: When rings or multiple concentric lines appear on the pearl’s surface, they are called spiral lines. If the rings completely encircle the pearl, it is termed a spiral pearl, often seen in Tahitian and freshwater pearls.
     • Pits: Small depressions or pits on the pearl’s surface caused by incomplete encapsulation of foreign matter or uneven nacre deposition.
     • Bumps and Depressions: These include raised (bumps) and sunken (soft depressions) areas. Bumps are due to excessive local deposition of nacre, while depressions result from insufficient deposition. Both are associated with unstable growth conditions.
     • Wrinkled Surface: Uneven or wrinkled surfaces caused by health issues in the mollusk or poor farming conditions.
     • Cracks: Surface cracks or damage caused by external impacts or detachment from the shell during harvesting.
   • b. Processing Flaws:
     • White Spots: Improper use of cleaning agents or chemicals may corrode the pearl’s surface, causing discoloration, spots, or etching, especially with acidic or highly alkaline substances.
     • Scratches and Abrasions: Fine scratches or abrasions caused during cleaning, polishing, or buffing with improper tools or excessive force.
     • Cracks: Some pearls undergo heat treatment to enhance color or stability, but improper high-temperature treatment can lead to surface cracks.
3. Flaw Quantity: The more flaws a pearl has, the lower its value.
4. Flaw Size: The size of the flaws and their proportion to the pearl’s surface significantly affect its value.
5. Flaw Position: The location of flaws directly impacts a pearl’s value. For example, if a pearl used in a ring has flaws near the drill hole, which can be cleverly concealed during setting, the impact on overall appearance and value is minimal. However, if flaws are on the opposite side or front, they significantly reduce value. Similarly, flaws on the front of a pearl for a necklace also lower its worth.

V. Luster

1. Factors Affecting Luster: Pearl luster results from light reflection, diffraction, and interference within the calcite and aragonite layers. The quality of luster depends on the following factors:
   • Nacre Thickness: Luster greatly depends on the nacre’s thickness. Generally, the thicker the nacre, the better the internal light reflection and interference, resulting in a richer luster.
   • Nacre Structure: Luster primarily comes from the nacre layer, especially the arrangement of aragonite crystals. These crystals resemble carefully arranged tiles. Their size, shape, uniformity, and density are crucial. When the crystals are densely and orderly arranged, they effectively reflect light, creating a bright and sharp luster.
   • Other Factors: The health of the mollusk, farming environment, cultivation period, nucleus selection, and post-harvest processing.
2. Luster Evaluation and Value: The stronger the luster, the higher the pearl’s value. Luster strength is determined by observing light reflection on the pearl:
   • Very Strong: Excellent luster, almost metallic or mirror-like, with clear reflection outlines.
   • Strong: Good luster with obvious reflection outlines.
   • Medium: Bright luster, resembling glass.
   • Average: Moderate luster.
   • Weak: Dull luster, resembling wax or fish scales.

VI. Color

1. Overview: Pearl color is determined by three elements: body color, overtone, and orient.
2. Body Color: This refers to the primary color of the pearl, determined by selective absorption of white light by the nacre, influenced by proteins (conchiolin) in the nacre. Common body colors include white, cream, pink, silver-gray, and black.
3. Overtone: Also known as interference color, overtone refers to a secondary, transparent color reflected on the pearl’s surface under specific light. This is caused by multiple reflections and interference of light within the nacre. Common overtones are pinkish and greenish hues. Dyed pearls do not exhibit overtone, though irradiated pearls may have overtone and orient.
4. Orient: A rainbow-like iridescence that shimmers on or just beneath the pearl’s surface. Irregular surfaces make orient more likely to appear. Its formation depends on the quality and arrangement of aragonite crystals in the nacre.
5. Color Value Evaluation:
   • Pure and Vibrant Body Color: High-quality pearls often exhibit pure white or deep black body colors.
   • Bright and Harmonious Overtone: Enhances the pearl’s beauty and rarity. Pearls with pink or greenish overtones are often more desirable.
   • Presence of Orient: Pearls with orient are higher in quality under similar conditions.
   • Uniformity: Even distribution of body color and overtone across the pearl is a key evaluation criterion.
   • Naturalness: Natural body and overtone colors are more valued than dyed pearls, as they reflect the pearl’s inherent beauty.
6. No Unified Color Standard: Color grading is influenced by rarity, fashion trends, and market preferences. For instance, yellow pearls are less valued in the U.S. and Japan but are more expensive in Southeast Asia. Personal preference and wearability are crucial, making pearl color difficult to quantify for grading systems.

VII. Size

1. Overview: Pearl size is measured in millimeters (mm), typically ranging from 5mm to 15mm. Larger pearls are more valuable under the same conditions. A 1mm difference can significantly affect price. For example, Akoya pearls’ price jump occurs at 8mm, with prices sometimes doubling above this size.
2. Factors Affecting Pearl Size: Pearl size depends on the mollusk species, the size of the implanted nucleus, and cultivation time.