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Feldspar

Moonstone

White, cream, or gray feldspar with adularescence

Gray White
Optical properties

Optical characteristics

Ref. index
1.518 – 1.572
Birefringence
0.005 – 0.01
Luster
Vitreous to pearly
Pleochroism
Variable Variable depending on transparency, orientation, and variety.
Fluorescence
Variable to inert.
Origins

Source localities

Myanmar Myanmar: Mogok Valley
Premium ★ Top Source

Classic source for ruby, sapphire, spinel and other collector gems.

34.2% est. supply
Sri Lanka Sri Lanka: Ratnapura / Elahera
Premium ★ Top Source

Classic Ceylon source for sapphire and many alluvial gems; known for bright colors and good clarity.

29% est. supply
Madagascar Madagascar: Ilakaka / Andranondambo region
Major

Modern major source for sapphire, garnet, beryl, quartz, tourmaline and many collector gems.

23.2% est. supply
India India: Rajasthan / Odisha / Karnataka
Notable

Historic and modern source for garnet, moonstone, corundum and other gems.

13.7% est. supply
Treatments

Enhancement & treatment

Surface Enhancement Waxing Waxing is a common minor surface enhancement. In jade it is often accepted when…
Inclusions

Inclusions & features

Optical Adularescence and Labradorescence With the naked eye and loupe: a glowing light effect that appears to float… Fractures Centipede Inclusions Under 10x loupe: rows of short stress fractures between alternating feldspar layers, arranged perpendicular… Crystals Crystal Inclusions Under 10x loupe: solid, well-formed mineral crystals trapped inside the host gem. They may… Fractures Feathers and Fractures Under 10x loupe: irregular internal surfaces that catch light and appear bright, wing-like, or… Fractures Fingerprint Inclusions Under 10x loupe: curved or wavy lines of tiny dots forming patterns that look… Clouds Pinpoint Clouds Under 10x loupe: concentrations of extremely tiny bright dots that individually are too small… Multiphase Two-Phase Inclusions Under 10x loupe: a transparent irregular cavity containing both a liquid phase and a…
Identification

Instruments used

Dichroscope Reveals pleochroism, instantly eliminates singly-refractive stones 10x Loupe Your most-used instrument, start every examination here Polariscope Determines single vs. double refraction, quick and conclusive Refractometer Measures refractive index, the backbone of gem identification UV Lamp, Long Wave and Short Wave Fluorescence exposes treatments, synthetics, and origin