Gem science
Methods and instruments that turn appearance into repeatable evidence while making the limits of each test explicit.
Refractometer
A core instrument for measuring refractive index and observing optical character.
With suitable contact and a polished facet, a refractometer can narrow identification through refractive-index readings. Rotating the stone helps reveal single or double refraction and birefringence, but over-the-limit stones require other methods.
- Measures
- Refractive index
- Useful observation
- Birefringence
- Common limit
- Approximately 1.81 on standard units
Spectroscopy
Absorption patterns connect visible colour to elements, defects, and treatment evidence.
A hand spectroscope can reveal diagnostic bands in some stones, while laboratory UV-Vis-NIR, infrared, Raman, and photoluminescence instruments probe different interactions. No single spectrum answers every origin or treatment question.
- Visible method
- Absorption spectroscopy
- Molecular method
- Raman spectroscopy
- Best practice
- Correlate multiple datasets
Microscopy
Magnification makes growth, treatment, damage, and manufacture visible.
Darkfield, brightfield, fibre-optic, diffused, and polarised illumination expose different features. The useful observation is not simply that an inclusion exists, but its form, relief, orientation, association, and response as lighting changes.
- Routine range
- Approximately 10×-60×
- Primary uses
- Identification, treatment, condition
- Essential variable
- Lighting geometry