Advanced Laboratory Instruments

• Emerald oil and resin detection: Natural fractures in emerald are commonly filled
  with cedar oil, synthetic resins (Opticon), or epoxy. Each filler produces
  characteristic IR absorption peaks distinct from the host beryl spectrum. Kiefert
  et al. (2000) demonstrated that FTIR identifies the filler type (oil vs resin vs epoxy)
  by peak position: Journal of Gemmology 26, 501–520 (DOI: 10.15506/jog.1999.26.8.501)
  [VERIFIED].

• Jadeite polymer treatment (Type B jade): Bleached and polymer-impregnated jadeite
  shows characteristic C–H and C=O absorption bands in the mid-IR that are absent in
  untreated (Type A) jadeite. Tan et al. (2013) confirmed FTIR distinguishes treated from
  untreated jade: COSMOS journal (DOI: 10.1142/s0219607713500031) [VERIFIED].

• Diamond type classification: FTIR distinguishes Type Ia (nitrogen in aggregates –
  A and B centres), Type Ib (isolated nitrogen), Type IIa (nitrogen-free), and Type IIb
  (boron-bearing, electrically conductive) by nitrogen absorption features in the mid-IR
  one-phonon region (~1000–1300 cm⁻¹). Type IIa diamonds lack nitrogen absorptions and
  are more likely candidates for HPHT treatment or CVD synthesis – triggering further
  investigation.

• Heat treatment indicator in sapphire: Delaunay (2024) showed that the 3232 cm⁻¹
  FTIR band provides new insights for identifying heat treatment in metamorphic-type blue
  sapphires: Journal of Gemmology 39(1) (DOI: 10.15506/jog.2024.39.1.33) [VERIFIED].

• Beryllium-diffused sapphire detection: Emmett et al. (2003) described UV-Vis-NIR
  signatures associated with beryllium diffusion – the process causes orange colouration
  in corundum through Fe³⁺–O²⁻ charge transfer bands in the UV, producing a reduction
  in blue absorption and strengthening of an absorption feature near 390 nm: Gems &
  Gemology 39(2), 84–135 (DOI: 10.5741/gems.39.2.84) [VERIFIED]. Be diffusion is
  confirmed definitively only by LA-ICP-MS (see below) – UV-Vis-NIR provides supporting
  evidence.

• Chromophore quantification: Distinguishes iron-coloured from chromium-coloured
  stones by the shape and position of absorption bands; quantifies relative contributions
  of Fe²⁺, Fe³⁺, Cr³⁺, and IVCT mechanisms.

• Origin indicators: The relative intensities of iron absorption bands in sapphire
  correlate with geological source (basaltic vs metamorphic origin) when combined with
  trace element data.

• Inclusion identification without destruction: The Raman spectrum of a solid inclusion
  (calcite, apatite, rutile, zircon, pyrite) inside a gemstone can be measured through the
  host stone using a confocal Raman micro-probe. Nassau (1981) was among the earliest to
  demonstrate "Raman Spectroscopy as a Gemstone Test": Journal of Gemmology 17(5), 306–320
  (DOI: 10.15506/jog.1981.17.5.306) [VERIFIED].

• Filler identification in emerald: Kiefert et al. (2000) used both IR and Raman to
  identify filler substances in emeralds; Raman provides complementary data to FTIR for
  distinguishing oil types (DOI: 10.15506/jog.1999.26.8.501).

• Jade species determination: Raman spectra of nephrite and jadeite are distinct; Tan
  et al. (2013) confirmed Raman and FTIR together reliably separate the two jade species
  (DOI: 10.1142/s0219607713500031).

• Rapid portable screening: Tsai et al. (2023) reported rapid gem mineral
  identification using portable Raman: Journal of Raman Spectroscopy
  (DOI: 10.1002/jrs.6518) [VERIFIED].

Energy-Dispersive X-ray Fluorescence (EDXRF): An X-ray beam causes emission of
characteristic secondary X-rays from elements in the sample, providing non-destructive
elemental analysis down to ppm levels for elements with atomic number ≥ 11 (sodium).

• Non-destructive; no sample preparation required.
• Cannot detect elements below atomic number ~11 in standard configurations.
• Cannot detect beryllium (atomic number 4) – this is a critical limitation for
  Be-diffusion treatment detection; only LA-ICP-MS can routinely detect Be.
• Schmetzer et al. (2009) used EDXRF for gem corundum origin fingerprinting: Gems &
  Gemology 45(4), 264 (DOI: 10.5741/gems.45.4.264) [VERIFIED].

Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS): A laser
micro-beam ablates a tiny spot (10–100 µm); the ablated material is carried into an ICP
plasma and analysed by mass spectrometry, providing trace and ultra-trace element data
to ppb levels. Micro-destructive – leaves a tiny ablation pit.

• Origin fingerprinting in corundum: Basaltic-origin sapphires (Australia,
  Thailand/Cambodia, Nigeria) have high Fe (>5000 ppm), high Ga/Al ratios, and are
  essentially Cr-free. Metamorphic-origin sapphires (Kashmir, Sri Lanka, Myanmar) have
  lower Fe, measurable Cr, higher Mg, and lower Ga. Sutherland et al. (2014) advanced
  trace element fingerprinting for gem corundum using LA-ICP-MS and EDXRF: Minerals
  5(1) (DOI: 10.3390/min5010061) [VERIFIED].
• Beryllium detection: Only LA-ICP-MS can routinely detect Be (atomic number 4),
  making it the definitive test for Be diffusion treatment. Emmett et al. (2003) confirmed
  this (DOI: 10.5741/gems.39.2.84).
• Limitation: Requires certified reference materials for calibration; results
  depend on reference database quality for origin assignment.

• HPHT-treated Type IIa diamonds: HPHT treatment converts brown Type Ia diamonds to
  near-colourless Type IIa stones by dissolving nitrogen aggregates. At 77 K, PL reveals
  the presence or absence of the 637 nm NV⁰ centre (neutral nitrogen-vacancy) and the
  575 nm NV⁻ centre (negatively charged NV). Lim et al. (2010) demonstrated
  discrimination between natural and HPHT-treated Type IIa diamonds using PL: Diamond and
  Related Materials 19(10), 1254–1258 (DOI: 10.1016/j.diamond.2010.06.007) [VERIFIED].

• CVD synthetic diamond: Willems et al. (2011) explored luminescent regions in CVD
  synthetic diamond using PL – CVD diamonds show characteristically different luminescence
  patterns related to their growth sectors: Gems & Gemology 47(3), 202–207
  (DOI: 10.5741/gems.47.3.202) [VERIFIED].

• H3 and NV centre discrimination: The presence of H3 (504 nm), NV⁻ (637 nm), and
  their relative intensities at 77 K can distinguish HPHT-treated from natural fancy-colour
  diamonds. Natural Type IIa diamonds have a characteristic PL signature distinct from
  HPHT-treated Type Ia stones.