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Laser Raman microspectroscopy on gem inclusions: identifying negative crystals in sapphire?

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E
Elena Spectra•910 rep

How do laboratory Raman spectrometers non-destructively identify microscopic mineral inclusion phases trapped inside rough corundum crystals?

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5 Answers from travellers

✓Accepted Answer

Laser Raman microspectroscopy has revolutionized gemmological inclusion analysis by providing non-destructive mineral identification. By focusing a monochromatic laser beam (typically 532nm or 785nm) through a microscope objective directly onto a microscopic crystal or fluid inclusion trapped inside a sapphire or ruby, analysts record inelastic scattering (Raman shifts). Every mineral phase produces a unique molecular vibrational fingerprint spectrum. This allows lab gemmologists to differentiate rutile needles, zircon crystals, monazite, apatite, and artificial glass fillings without damaging the host gemstone.

38
D
Dr Kularatne Lab•1950 rep

Confocal Raman optics allow focusing the laser spot onto inclusions buried 2mm beneath facet surfaces without requiring table window polishing.

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E
Elena Spectra•910 rep

Gas-liquid two-phase inclusions analyzed via Raman laser confirm the presence of high-density carbon dioxide inside metamorphic gem host crystals.

18
L
Lars Crust•915 rep

Fluorescing host gems can obscure weak Raman spectra; selecting appropriate laser wavelengths (such as 785nm NIR) minimizes background fluorescence interference.

15
M
Max Rigging•925 rep

NGJA and international gem testing labs rely on Raman fingerprinting to issue absolute guarantees against treated glass-filled composite gemstones.

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C
Clara Gastronomy•885 rep

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