Akoya Pearl | Gemopedia

Akoya pearls tend to be the most consistently round and near-round pearls, which makes them perfect for matching for multi-pearl jewelry. Akoyas are saltwater pearls prized for their roundness, luster and color. They tend to be small, ranging from two to 11 millimeters, as the akoya oyster is the smallest producing oyster, and are considered the "classic" pearl, with their generally white to cream color, with rose or silver overtones.
Alternate
Names
Akoya-Gai
Colors
White, Cream Pink, Yellow, Blue With Rose, Green Overtone

Akoya Pearl Classification

Common Name

Akoya Pearl

Species

NA

Variety

Akoya Pearl

Colors

White, Cream Pink, Yellow, Blue With Rose, Green Overtone

Alternate Names

Akoya-Gai

Gemstone Groups

Key Separations

Appearance, 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.

Comments

Typical size of akoya pearls are 2 to 11mm. They have the highest luster among pearls. They are produced by the Pinctada martensii (Pinctada fucata) mollusk.

Akoya Pearl Optical Properties

Transparency

Translucent - Opaque

Refractive Index

1.53-1.685

Birefringence

0.155

Optic Character

NA

Optic Sign

NA

Polariscope Reaction

Aggregate (AGG)

Fluorescence

SWUV: Variable
LWUV: Variable

CCF Reaction

Pleochroism

None

Dispersion

Comments

Akoya Pearl Chemistry & Crystallography

Chemical Name

calcium carbonate + conchiolin and water

Chemical Formula

CaCO3

Synthesis

Crystal System

NA

Classification

Organic

Nature

Cultured

Crystallinity

Comments

Akoya Pearl Characteristic Physical Properties

Hardness

2.5-4

Streak

Specific Gravity

2.72-2.78

Toughness

Good

Inclusions

Akoya pearls have an intense luster and iridescent surface. If the pearl is drilled you can inspect the hole to look for bead nucleus.

Luster

Dull

Stability

Poor

Fracture

Uneven

Cleavage

None

Comments

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