Organic
Coral
Biogenic calcium carbonate coral
Pink
Red
White
Optical characteristics
- Ref. index
- 1.49 – 1.66
- Luster
- Waxy to dull
- Pleochroism
- None Variable depending on transparency, orientation, and variety.
- Fluorescence
- Variable to inert.
Source localities
Enhancement & treatment
Inclusions & features
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…
Instruments used
Dichroscope
Reveals pleochroism, instantly eliminates singly-refractive stones
Hydrostatic Scale
Measures specific gravity, works even on opaque 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