Gemology Fast Track / Unit 8 of 24 · Instruments · 60 min
SG kit, UV, spectroscope, testers — and what to buy
Goal: Know every instrument, what it proves, and a buying order.
UV lamp (long-wave 365 nm / short-wave 254 nm)
Strong red (LW)
Ruby (Burmese strongest), red spinel, some synthetic ruby even stronger.
Blue (SW)
Benitoite (strong), scheelite (bluish-white), many diamonds blue under LW.
Green / yellow-green
Hyalite opal (uranium), willemite, some glass.
SW UV damages eyes and skin. Never look into the lamp; use a viewing box.
Hand spectroscope: the fingerprints worth knowing
Chromium — rubyFine doublet 694/692 (may show bright emission), broad yellow-green band, blue lines.
Chromium — emeraldDoublet ~683/680, line 637, weak broad band in yellow.
Iron — almandineThree strong bands ~505, 527, 576 nm.
Iron — blue sapphire450 nm band (strong in basaltic stones).
Cobalt — synthetic spinel / glassThree broad bands; real sapphire never shows this.
ZirconMany fine lines; 653.5 nm diagnostic.
JadeiteSingle line at 437 nm.
Rare earths (didymium) — apatiteDoublet ~580 nm in yellow apatite, some sphene.
Other handheld testers
Thermal diamond tester
Diamond conducts heat. Moissanite also passes.
Moissanite / multi-tester
Electrical conductivity separates moissanite. Needed if you handle diamonds.
Strong magnet
N52 neodymium: garnets with Fe/Mn drag; hematine clings; quick sorting tool.
Calipers
Digital 0.01 mm: weight estimation, rough yield planning.
Lab-only instruments (know what to ask a lab for)
FTIR — treatments, polymer in jade, syntheticsRaman — mineral ID, inclusionsUV-Vis-NIR — colour cause, dyes, Be-diffusion cluesEDXRF / LA-ICP-MS — trace elements, origin, Cu in Paraíba, BePhotoluminescence — diamond types, heat in spinelDiamondView — lab-grown diamond growth patternsX-ray / micro-CT — natural vs cultured pearl
Buying order for you
Prices change; treat them as indicative.
Practical
Decide your kit using the buying table. If you trade coloured stones in Bangkok, a loupe + refractometer + polariscope + dichroscope + Chelsea filter + carat scale for SG covers most daily IDs; the microscope comes next.
Unit quiz
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