Origin Determination Overview
Introduction to geographic origin determination for gemstones including methodology, premium factors, and laboratory reports.
Introduction
Geographic origin determination identifies the locality where a gemstone formed.
Origin can significantly affect value, with certain sources commanding substantial
premiums due to historical significance, quality associations, or rarity.
Origin is determined through careful analysis of inclusion suites, trace element
chemistry, and growth characteristics.
Why Origin Matters
Premium Factors
- Historical prestige (Kashmir, Burma, Colombia)
- Consistent quality association
- Rarity of production
- Market perception and demand
- Collector interest
Practical Considerations
- Treatment likelihood varies by origin
- Ethical sourcing concerns
- Investment and resale value
- Insurance and documentation
- Trade and customs regulations
Origin Determination Methods
Inclusion Analysis
The primary method for origin determination. Characteristic inclusions form
fingerprints unique to specific geological environments:
- Mineral inclusions: Identify host rock and formation conditions
- Fluid inclusions: Reveal formation fluids and temperatures
- Growth patterns: Record crystallization history
- Solid inclusion assemblages: Diagnostic for specific localities
Trace Element Chemistry
Advanced spectroscopic techniques measure trace elements that vary by deposit:
- LA-ICP-MS: Laser ablation inductively coupled plasma mass spectrometry
- LIBS: Laser-induced breakdown spectroscopy
- ED-XRF: Energy-dispersive X-ray fluorescence
Ratios of elements like Fe, Ti, Ga, V, and Cr help distinguish origins.
Spectroscopic Features
- UV-Vis-NIR absorption spectra
- Photoluminescence characteristics
- Infrared spectroscopy
- Raman spectroscopy for inclusion identification
Major Laboratories
| Laboratory | Location | Known For |
|---|---|---|
| Gübelin | Switzerland | Pioneering inclusion research |
| SSEF | Switzerland | Origin determination expertise |
| GIA | USA/Worldwide | Comprehensive testing |
| AGL | USA | Coloured stone expertise |
| GRS | Switzerland/Asia | Origin and quality reports |
| Lotus Gemology | Thailand | Independent origin analysis |
Report Terminology
Understanding laboratory report language:
- "Consistent with...": Inclusions match known characteristics
- "Origin undeterminable": Insufficient diagnostic features
- "Heat treatment: None": No evidence of heating detected
- "Heat treatment: Evidence of...": Signs of thermal treatment
Limitations
Origin determination has inherent limitations:
- Some deposits produce material with overlapping characteristics
- Heavily included or treated stones may be difficult to assess
- New deposits may initially lack reference samples
- Different labs may reach different conclusions
- Origin reports represent the laboratory's opinion based on current knowledge