Lesson23: Pearl Identification

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Methods to Identify Natural vs. Artificial Pearls

1. Luster Inspection
   Artificial pearls often exhibit intense and uniform luster, while natural pearls display a more subdued, soft radiance with slight color nuances.
2. Surface Analysis
   Artificial pearls typically have a flawless, smooth surface. In contrast, natural pearls may show minor irregularities such as small blemishes or natural growth lines.
3. Skin Texture
   Artificial pearls may have grainy or spotted coatings caused by uneven application or layering. Natural pearls, on the other hand, feel smooth and fine to the touch.
4. Matching Uniformity
   Artificial pearls are usually consistent in size, shape, and color, resulting in high uniformity across strands. Natural pearls, however, exhibit subtle variations, making each one unique.
5. Density and Weight
   Artificial pearls have lower density, making them feel lighter when held. Natural pearls are often denser and feel heavier.
6. Drilled Hole Characteristics
   Artificial pearls, especially glass or plastic varieties, often show chipping or uneven edges around drilled holes. Natural pearls generally maintain smooth, intact surfaces near drilled areas.
7. Layer Durability (Test Not Recommended)
   Gently rubbing two pearls together reveals differences: natural pearls might emit a soft powdery residue, while artificial pearls may not. Finger rubbing may also produce a fine pearl powder for natural pearls without causing damage.

• Fake pearls have jagged drill holes. (Left)
• Real pearls have smooth drill holes. (Right)

Identifying Dyed Pearls and Irradiated Pearls

1. Dyed Pearls
   • Color Distribution: Dyed pearls often show uneven coloring or concentrated pigments around imperfections. Some dyed silver-toned pearls may have black or grey stains if tested with a 2% nitric acid solution.
   • Luster Observation: Natural pearls exhibit a warm, radiant glow, while dyed pearls appear dull with uniform, unnatural coloring.
   • Powder Scraping: Natural pearls yield white powder when scratched, while dyed pearls’ powder tends to show color.
   • Size and Price: Suspiciously low-priced pearls of specific sizes, such as small black pearls labeled as “Tahitian” or “South Sea,” may actually be dyed Akoya pearls.
2. Irradiated Pearls
   • Color Changes: Irradiation can cause pearls to darken into shades like black, bronze, or green. Research attributes these changes to small quantities of manganese in the pearl’s composition.
   • Luster and Surface: The heat generated during irradiation can make the pearl layer slightly swell and disrupt water dispersion, resulting in irregular fractures under the surface.
   • Hole Inspection: For nucleated pearls, irradiation often creates darker tones near the nucleus.
   • Fluorescence Reaction: Natural pearls exhibit unique fluorescence under UV light, unlike irradiated pearls, which show no such luminescence.

Distinguishing Market-Confused Pearls

• Akoya vs. Freshwater Pearls
  • Surface Observation: Akoya pearls may show a distinctive glass-like surface texture, absent in freshwater pearls.
  • Component Analysis: Akoya pearls generally have lower manganese levels compared to freshwater varieties, allowing for differentiation through compositional analysis.
  • X-ray Fluorescence: Akoya pearls typically exhibit a specific fluorescence pattern under X-rays, with more pronounced green hues compared to freshwater pearls.
• South Sea Pearls vs. Edison Pearls
  1. Surface Luster: If a pearl exhibits noticeable dimples or blemishes, it is likely an Edison pearl, as South Sea pearls rarely have such flaws.
  2. Pit Depth: Thicker surface layers in pearls with deep pits suggest they are South Sea pearls.
  3. Color Observation: A pearl with a clear yin-yang color contrast is most likely an Edison pearl.
  4. Component Analysis: Edison freshwater pearls typically contain higher manganese levels than South Sea saltwater pearls. X-ray fluorescence data helps verify this distinction.
  5. X-ray Fluorescence: When comparing the fluorescence under X-rays, South Sea pearls generally show a greenish fluorescence, while Edison pearls typically exhibit a yellowish fluorescence. The fluorescence of Edison pearls tends to be stronger on the surface, whereas South Sea pearls emit fluorescence from within. When inspecting drilled holes, the fluorescence within the hole of a South Sea pearl is more intense compared to the surrounding area.