Spectroscopy Analysis
Overview
Spectroscopy examines how gemstones absorb different wavelengths of light. The absorption pattern creates a unique "fingerprint" for each gem species and can reveal treatments.
How It Works
Light passes through the gem and is analyzed by a spectroscope. Certain wavelengths are absorbed by trace elements, creating dark bands or lines in the spectrum that are characteristic of specific gems.
Equipment Needed
- Hand-held spectroscope or desktop spectrometer
- Strong light source (fiber optic or LED)
- Dark room for observation
- Wavelength calibration source
Procedure
- Position the gem between the light source and spectroscope
- Adjust focus until the spectrum is sharp
- Note the position and intensity of absorption bands
- Compare observed pattern with reference spectra
- Document findings with wavelength measurements
Typical Values / Results
| Gemstone | Value / Observation |
|---|---|
| Ruby | 694nm fluorescence doublet, 659/668nm absorption |
| Blue Sapphire | 450nm (iron), 471nm bands |
| Emerald | 683nm (chrome lines), 680nm doublet |
| Alexandrite | Chrome spectrum similar to emerald |
| Almandine Garnet | Broad bands at 505nm, 520nm, 573nm |
Limitations
Pale gems may show weak absorption. Some synthetics have identical spectra to natural gems. Requires practice to interpret correctly.