Nacre Thickness

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Nacre is the iridescent layers which are produced by the mollusk to coat the nucleus. Looking through the drill hole of a pearl with a 10x loupe, or twirling the pearl around to see how transparent the bead is are ways of evaluating nacre thickness.
  • Very thick: 0.5mm (millimeter) of nacre, approximately 2 years of cultivation. Can not see any nucleus with unaided eye
  • Thick: .45mm of nacre, approximately 1 - 2 years of cultivation. Can not see any nucleus with unaided eye
  • Medium: .35mm of nacre, approximately 1- 1 years of cultivation. Nucleus not visible with unaided eye
  • Thin: .30mm of nacre, approximately 9 months to 1 year of cultivation. To the unaided eye the pearls appear to blink when twirled
  • Very thin: .25mm of nacre, approximately under 9 months cultivation. To the unaided eye pearls have fisheye look, nucleus lines are visible
Nacre Thickness Cultivation Time Grade
Very thick 2 years 10
Thick 1 -2 years 9
Medium 1- 1 years 7-8
Thin 9 months-1 year 4-6
Very thin under 9 months 1-3

Evaluating Factors

Overtone Color
Body Color
Shape
Size
Lustre
Nacre Thickness
Blemishes
Matching
Final Grade
Worksheet
Pricing
Pile of Pearls

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