Gemmology Instruments

Flashcards on gemmology instruments

Luminescence effects

The emission of ‘cold’, non-incandescent, visible light by a substance.

Fluorescence

The emission of visible light by a substance whilst it is being excited by radiation of higher energy (shorter wavelength).

Phosphorescence

Occurs when radiation is emitted by a material irradiated by a higher-energy source, during and after the removal of the source irradiation.

UV Light Use in Gemmology

Used for backing up observations, indicating further testing, separating stones, and gem prospecting.

UV-Vis Spectrometer

Can provide information about natural vs. synthetic, treated or untreated stones, including country of origin.

X-ray machines in gemmology

Used for radiography (looking into/through materials) and observation of X-ray luminescence.

X-Ray Fluorescence spectrometers (XRF)

Analysis of X-rays re-emitted by a material when excited by X-rays, detecting the presence and concentration of chemical elements.

Infrared (IR) radiation

Wavelength longer than visible light but shorter than microwaves (750 nm – 1mm). Used in spectrometers and reflectance meters.

Infrared spectrometer use

Used in infrared spectrometers to measure absorption in material; useful for distinguishing natural from flux-melt emeralds and detecting synthetic resin (B-Jade).

Reflectance meters

Detects and measures the amount of light reflected by a gemstone surface, giving an indication of relative reflection power; used for testing and differentiating diamonds from simulants.

Raman spectrometer

Uses a strong beam of UV, visible light, or IR; detects energy re-emitted at a different level to identify rough/fashioned gems, inclusions, and treatments.

Cathodoluminescence (CL)

Uses an electron beam to stimulate visible light fluorescence, revealing internal features of a gem.

Thermal conductivity

Measures the ability of a material to transfer heat; used to distinguish diamonds from simulants (except synthetic Moissanite).

Moissanite testers

Detect electrical conductivity and differentiate from diamonds.

X-Ray fluorescence

Detects the presence and concentration of chemical elements within a specimen.

X-Ray diffraction

Used for crystal identification.

X-Ray Luminescence

Used to differentiate between salt water pearls and fresh water pearls (which has luminescence).