Kasumiga Pearl

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June Birthstone

In 1996 a German company started marketing Japanese Freshwater Pearls as Kasumiga Pearls. The average size of these are between 10mm to 15mm but can grow up to 20mm. Kasumiga Pearls are known for their excellent color and luster. The most valuable pearls are round to near round but they also come in interesting baroque shapes.

Kasumiga Pearl Polished
Kasumiga Pearl Classification
Common Name Kasumiga Pearl
Species Pearl
Kasumiga Pearl Optical Properties
Transparency Opaque-Translucent
Dispersion Strength: None
Refractive Index 1.530-1.685
Birefringence 0.155
Optic Character NA
Optic Sign NA
Polariscope Reaction Aggregate (AGG)
Fluorescence SWUV: Cream/light yellow: inert to very weak green; Cream: inert; Pink/purple/golden extremely weak chalky green or bluish green; Orange: inert
LWUV: Cream/light yellow: weak chalky green blue; Cream: blue; Pink/purple/golden Inert to very weak chalky green or bluish green; Orange: inert
Pleochroism None
Kasumiga Pearl Characteristic Physical Properties
Streak White
Toughness Good
Inclusions Sometimes they will show black or brown blemishes that are remnants of organic matter. You might see aragonite platelets under magnification.
Luster Pearly
Stability Fair
Fracture Uneven
Cleavage None
Kasumiga Pearl Chemistry & Crystallography
Chemical Name calcium carbonate + conchiolin and water
Chemical Formula CaCO3
Crystal System NA
Chemistry Classification Organic

Kasumiga Pearl Colors

  • Gray Kasumiga Pearl Gray
  • Purple Kasumiga Pearl Purple
  • Pink Kasumiga Pearl Pink
  • Brown Kasumiga Pearl Brown
  • Orange Kasumiga Pearl Orange
  • Blue Kasumiga Pearl Blue
  • Yellow Kasumiga Pearl Yellow

Alternate Names

Kasumi Pearls, Japanese Cultured Freshwater Pearl

Countries of Origin



Lake Kasumigaura is Japan’s second largest lake. Pearl farming was first initiated at the lake in 1931 but it did not gain prominence until the 1980’s when pearl farming at Lake Biwa began to decline. The oysters that are used for pearl farming are hybrids of the Hyriopsis schlegelii and Hyriopsis cumingii oysters. All the pearls are bead nucleated and the growth period is between 3.5 to 4 years.


Avoid cosmetics, perfumes, hairsprays, heat and household chemicals. Pink Kasumiga pearls will fade if exposed to heat.

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Tim Matthews


Tim Matthews

Tim Matthews is President and Chief Executive Officer of Jewelry Television® (JTV), as well as a member of the company's Board of Directors. He oversees and leads all aspects of the company's powerful omni-digital retail platform that uniquely specializes in fine jewelry and gemstones. His passion for business and gemstones has led him to become a recognized expert in the field of gemology. He is a life member of the Gemmological Association of Great Britain (Gem-A) and has earned Gem-A's highest degrees, the Gemmology (FGA) and Diamond (DGA) diplomas. He is also a Graduate Gemologist (GG) of the Gemological Institute of America (GIA) and has also completed GIA's Graduate Diplomas in Diamonds, Colored Stones and Pearls. Under his leadership, JTV has become the leader in the sourcing and selling of color gemstones and jewelry.

This page was created on June 27, 2014.

This page was last edited on October 24, 2019.