Keshi Pearls Gemstone & Information | Gemopedia by JTV | Gemopedia™
A happy accident of pearl farming, keshi pearls are produced by chance. Saltwater oysters sometimes reject their bead implant, but particles of the accompanying mantle tissue remain and stimulate the production of nacre in flat, petal-like shapes. They are often removed as seed pearls, inspiring their name, meaning "poppy seed" in Japanese. While some people think they should be considered natural pearls, they are a by-product of the culturing process so this is not technically correct. One of the most striking characteristics of South Sea keshi pearls is their very intense luster and iridescence, sometimes greater than seen in the finest cultured pearls.
Almost Any Color Usually White, Cream
Keshi-pearls classificationCommonNameKeshi PearlsSpeciesNAVarietyKeshi PearlsColorsAlmost Any Color Usually White, CreamAlternateNamesChance PearlsGemstoneGroupsKeySeparationsAppearance, RI, birefringence blink and magnification. A "tooth test" is commonly used in which a pearl is rubbed against a tooth; if gritty, this is an indication that the surface is nacre, versus plastic and glass imitations that feel smooth.ClassificationCommentsKeshi pearls are usually off round or baroque because they were formed from the mantle tissue from a rejected implantation. They are becoming rare in the market due to improved culturing techniques. Keshi pearls can be freshwater SG: 2.66 to 2.78 or Saltwater SG: 2.61 to 2.85.
Keshi-pearls chemistry & crystallographyChemicalNamecalcium carbonate + conchiolin and waterChemicalFormulaCaCO3SynthesisCrystalSystemOrthorhombicChemistryClassificationOrganicNatureCulturedCrystallinityChemistryComments
Keshi-pearls optical propertiesTransparencyTranslucent - OpaqueDispersionOpticalCommentsRefractiveIndex1.53-1.685Birefringence0.155OpticCharacterNAOpticSignNAPolariscopeReactionAggregate (AGG)FluorescenceSWUV:
Keshi-pearls characteristic physical propertiesHardness2.5-4CharacteristicCommentsStreakSpecificGravity2.61-2.85ToughnessGoodInclusionsKeshi pearls have intense luster and iridescent surface.LusterDullStabilityFairFractureUnevenCleavageNone