| Zircon |
- 653.5 nm — Diagnostic zircon line (strong; the most distinctive zircon band, visible in most high-type specimens)
- 659 nm — Zircon line (moderate; closely spaced with 653.5nm; together form a distinctive pair)
- 621 nm — Zircon absorption line (moderate)
- 615 nm — Zircon absorption line (moderate)
- 589 nm — Zircon line (weak to moderate)
- 562 nm — Zircon line (weak; part of the characteristic 'staircase' spectrum)
- 537 nm — Zircon line (weak)
- 516 nm — Zircon line (weak; staircase pattern continues)
|
| Alexandrite |
- 680.3 nm — Cr³⁺ doublet (strong, diagnostic; the narrower line of the alexandrite doublet)
- 678.5 nm — Cr³⁺ doublet companion (strong; broader companion line)
- 665 nm — Cr absorption band (moderate)
- 645 nm — Cr absorption band shoulder (moderate)
- 580–620 nm — Broad absorption in orange region causing red/green color change
|
| Iolite |
- 645 nm — Fe²⁺ band (strong; primary absorption in blue/violet iolite)
- 593 nm — Fe²⁺ band (strong; diagnostic for iolite)
- 585 nm — Fe²⁺ band (strong; part of diagnostic iron band group)
- 535 nm — Fe²⁺ band (moderate; mid-spectrum iron absorption)
- 492 nm — Fe²⁺ band (moderate)
|
| Ruby |
- 694.2 nm — Cr³⁺ fluorescence line (strong, diagnostic; the stronger line of the ruby doublet; also visible as emission in fluorescence)
- 692.8 nm — Cr³⁺ fluorescence line (strong; paired line of the diagnostic doublet)
- 659 nm — Cr³⁺ absorption band (moderate; internal absorption in the red region)
- 620 nm — Cr³⁺ broad absorption region (strong; part of broad green/yellow-green absorption band)
- 476 nm — Cr³⁺ band (strong; part of broad blue-violet absorption causing complementary red color)
|
| Spessartite Garnet |
- 432 nm — Mn²⁺ absorption band (strong; primary diagnostic band, most prominent in spessartite)
- 420 nm — Mn²⁺ band (strong; short wavelength manganese band)
- 412 nm — Mn²⁺ band (moderate; part of distinctive blue-violet Mn absorption group)
- 504 nm — Fe²⁺ band (moderate; if Fe-bearing spessartite; pyrope-spessartite solid solution)
- 520 nm — Fe²⁺ band (moderate; secondary iron band)
|
| Spinel |
- 685 nm — Cr³⁺ doublet (strong, red/pink natural spinel)
- 684 nm — Cr³⁺ doublet companion (strong, red/pink natural spinel)
- 533 nm — Cobalt band (strong, diagnostic for synthetic cobalt blue spinel)
- 580 nm — Cobalt band (strong, diagnostic for synthetic cobalt blue spinel)
- 619 nm — Cobalt band (strong, diagnostic for synthetic cobalt blue spinel)
|
| Almandine Garnet |
- 504 nm — Fe²⁺ band (strong, primary; most diagnostic band of the almandine trio)
- 520 nm — Fe²⁺ band (strong; central band of the diagnostic yellow-green trio)
- 573 nm — Fe²⁺ band (strong; third band completing the diagnostic trio)
- 527 nm — Fe²⁺ secondary band (moderate)
|
| Cubic Zirconia |
- Colorless CZ: no diagnostic absorption bands in the visible spectrum
- Erbium-doped CZ: 518 nm and 524 nm — sharp doublet absorption lines in the green (strong; rare-earth Er³⁺); additional lines in violet, blue, and red
- Holmium-doped CZ: ~540 nm — narrow absorption in the green (strong; rare-earth Ho³⁺)
- Neodymium+erbium-doped CZ (tanzanite simulant): ~485–490 nm, ~520–525 nm, ~650 nm (broad group) — rare-earth absorption complex
|
| Demantoid Garnet |
- 701 nm — Fe³⁺ band (strong; primary iron band for andradite/demantoid garnet)
- 640 nm — Cr³⁺ band (moderate; chromium absorption in Cr-rich specimens)
- 620 nm — Fe³⁺ band (moderate)
- 443 nm — Fe²⁺ band (strong; characteristic blue-violet absorption band for demantoid/andradite garnet)
|
| Emerald |
- 683 nm — Cr³⁺ doublet line (strong, diagnostic; primary line of emerald's chromium doublet)
- 680 nm — Cr³⁺ doublet companion (strong; paired with 683nm line, diagnostic for chromium coloration)
- 477 nm — Cr³⁺ broad absorption band (strong; causes absorption of violet-blue light)
- 427 nm — Cr³⁺ band (moderate; short wavelength chromium band)
|
| Pink Diamond |
- N3 415 nm
- H3 503 nm
- NV 575 nm
- NV 637 nm
|
| Tsavorite Garnet |
- 438 nm — V³⁺ broad absorption band (strong; primary vanadium band causing absorption of violet and transmission of green; diagnostic for vanadium-colored tsavorite)
- 610 nm — V³⁺ absorption band (moderate; secondary vanadium band in orange-red region; part of the diagnostic V³⁺ absorption pair with 438 nm)
- 630 nm — Cr³⁺ absorption line (moderate; chromium doublet band present in high-Cr tsavorites; forms pair with ~690 nm band)
- 690 nm — Cr³⁺ absorption line (moderate; red-region chromium band present in Cr-bearing tsavorites; note: 701 nm is an Fe³⁺ band characteristic of andradite/demantoid and does NOT occur in tsavorite)
|
| Yellow Diamond |
- N3 415 nm
- Cape 452 nm
- Cape 465 nm
- H3 503 nm
|
| Aquamarine |
- 537 nm — Fe²⁺ band (strong; primary diagnostic iron band for aquamarine)
- 456 nm — Fe²⁺ band (moderate; iron absorption in violet-blue region)
- 427 nm — Fe²⁺ band (weak to moderate; short wavelength iron band)
|
| Brown Diamond |
- N3 415 nm
- H3 503 nm
- GR1 741 nm
|
| Chrome Diopside |
- 690 nm — Cr³⁺ doublet line (strong; primary diagnostic chromium band for chrome diopside)
- 686 nm — Cr³⁺ doublet companion (strong; paired with 690nm)
- 506 nm — Fe²⁺ band (moderate; iron absorption also present in diopside)
|
| Chrome Tourmaline |
- 637 nm — Cr³⁺ line (strong; primary diagnostic chromium line in chrome tourmaline)
- 620 nm — Cr³⁺ band (moderate; secondary chromium band)
- 478 nm — Cr³⁺ broad absorption (strong; blue-violet chromium absorption region)
|
| Color-Change Sapphire |
- 450 nm — Fe²⁺/Fe³⁺ iron band (moderate; same as blue sapphire component)
- 693 nm — Cr³⁺ line (weak to moderate; responsible for red/purple component in incandescent light)
- 460 nm — Fe²⁺ iron band (moderate; contributes to blue component)
|
| Diaspore |
- 453 nm — Mn³⁺ absorption band (strong; responsible for the color-change effect in diaspore)
- 584 nm — Mn³⁺ band (moderate)
- 550 nm — Mn/Fe broad absorption (moderate)
|
| Enstatite |
- 506 nm — Fe²⁺ sharp diagnostic line (strong; characteristic of enstatite; most reliably seen in brownish/yellowish-green material)
- 427 nm, 546 nm — Fe²⁺ weaker bands (visible in iron-bearing specimens)
- 645 nm, 655 nm, 684 nm — Cr³⁺ bands (present only in chromium-bearing green enstatite; Cr³⁺ photoluminescence doublet at ~681–686 nm may also be seen)
|
| Heliodor |
- 537 nm — Fe²⁺ band (strong; primary diagnostic iron band, same as aquamarine but typically stronger in heliodor)
- 456 nm — Fe²⁺ band (moderate)
- 427 nm — Fe²⁺ band (weak)
|
| Hessonite Garnet |
- 432 nm — Mn²⁺ absorption band (moderate; iron-manganese grossular variety)
- 410 nm — Fe³⁺ band (weak to moderate; hessonite contains Fe-Mn in solid solution)
- 407 nm — Fe³⁺ band (weak)
|
| Hiddenite |
- 686 nm — Cr³⁺ line (strong; primary chromium line in hiddenite/spodumene)
- 669 nm — Cr³⁺ companion line (strong)
- 646 nm — Cr³⁺ band (moderate)
|
| Indicolite |
- 498 nm — Fe²⁺ band (strong; primary iron band in blue tourmaline)
- 455 nm — Fe²⁺ band (moderate)
- 640 nm — Fe²⁺ band (moderate; in deeply colored indicolite)
|
| Kunzite |
- 553 nm — Mn³⁺ absorption band (moderate; primary diagnostic band for kunzite/spodumene)
- 540 nm — Mn³⁺ band (moderate; paired with 553nm gives diagnostic doublet)
- 433 nm — Mn absorption shoulder (weak)
|
| Low-Type Zircon |
- 653.5 nm — Zircon line (weak to absent; low-type/metamict zircon shows fewer/weaker lines than high-type due to radiation damage)
- 659 nm — Zircon line (weak; may be absent in fully metamict specimens)
- Note — Lines progressively weaker as metamictization increases; fully metamict specimens may show no lines
|
| Peridot |
- 493 nm — Fe²⁺ band (strong; the strongest and most visible of the peridot iron trio)
- 473 nm — Fe²⁺ band (strong; second band of the diagnostic three-fingered absorption)
- 453 nm — Fe²⁺ band (moderate; third band completing the diagnostic trio in the blue-violet region)
|
| Pink Sapphire |
- 694 nm — Cr³⁺ line (moderate to strong; weaker than ruby; present in pink/red sapphire with Cr coloring)
- 692 nm — Cr³⁺ companion line (moderate; paired with 694nm)
- 476 nm — Cr³⁺ broad absorption (moderate; same as ruby but weaker at lower Cr concentrations)
|
| Pyrope Garnet |
- 505 nm — Fe²⁺ band (moderate; weaker than almandine; primary band of pyrope iron trio)
- 527 nm — Fe²⁺ band (moderate; central band)
- 575 nm — Fe²⁺ band (moderate; third band; trio less pronounced than almandine)
|
| Rhodolite Garnet |
- 505 nm — Fe²⁺ band (moderate; pyrope-almandine solid solution shows Fe bands)
- 520 nm — Fe²⁺ band (moderate; weaker than pure almandine)
- 573 nm — Fe²⁺ band (moderate; less pronounced than almandine trio)
|
| Sapphire |
- 450 nm — Fe²⁺/Fe³⁺ iron band (strong, primary diagnostic for blue sapphire)
- 460 nm — Iron band Fe²⁺ (moderate)
- 471 nm — Iron band (moderate, part of diagnostic iron trio)
|
| Sinhalite |
|
| Sphalerite |
- Fe²⁺ crystal-field band near 669–671 nm in red region (strong; clearly visible in hand spectroscope — diagnostic for sphalerite)
- Fe²⁺ crystal-field band near 698–702 nm in deep red region (strong; part of the diagnostic triplet)
- Fe²⁺ crystal-field band near 732–743 nm in deep red/near-infrared region (strong; third member of the Fe²⁺ triplet — note: attributed to Fe²⁺, not Cd²⁺ as older literature stated)
|
| Sphene |
- 586 nm — Fe³⁺ band (strong; primary diagnostic iron band for sphene/titanite)
- 532 nm — Fe³⁺ band (moderate)
- 497 nm — Fe³⁺ band (moderate; part of the distinctive sphene iron absorption group)
|
| Star Ruby |
- 694.2 nm — Cr³⁺ fluorescence line (strong; same as ruby; primary doublet line)
- 692.8 nm — Cr³⁺ fluorescence line (strong; paired doublet line)
- 476 nm — Cr³⁺ broad absorption (strong; blue-violet region absorption same as ruby)
|
| Synthetic Spinel |
- Co²⁺ absorption band near 540–545 nm in green region (strong; part of cobalt triplet — diagnostic for cobalt-coloured synthetic spinel)
- Co²⁺ absorption band near 580 nm in yellow-green region (strong; second member of diagnostic cobalt triplet)
- Co²⁺ absorption band near 625–635 nm in orange-red region (strong; third member of diagnostic cobalt triplet — the triplet as a whole is essentially diagnostic for Co-doped synthetic spinel vs natural iron-blue spinel)
|
| Tanzanite |
- 595 nm — V³⁺/Ti³⁺ absorption band (strong; vanadium/titanium causing the blue-violet color)
- 528 nm — V³⁺ band (moderate; vanadium absorption in green-yellow region)
- 455 nm — V³⁺ band (moderate; short wavelength vanadium band)
|
| Turquoise |
- Cu²⁺ absorption band near 432 nm in violet-blue region (strong; diagnostic — visible in hand spectroscope; most reliable hand-instrument test for copper content)
- Cu²⁺ absorption band near 460 nm in blue-violet region (weak; secondary band, sometimes visible as shoulder on the 432 nm feature)
- Fe³⁺ absorption near 689 nm in red region (present in iron-bearing specimens only; absent in pure Cu turquoise — useful to distinguish greenish Fe-rich material from blue Cu-rich material)
|
| Amazonite |
- Broad absorption band ~625–643 nm (blue color variety, Pb⁺ color center)
- Broad absorption band ~720–740 nm (green color variety, O⁻–Pb⁺ color center)
|
| Amethyst |
- 550 nm — Fe³⁺ broad absorption band (moderate; responsible for purple color in combination with color centers)
- 530 nm — Absorption shoulder (weak to moderate)
|
| Andalusite |
- 553 nm — Mn³⁺ absorption band (moderate; responsible for green pleochroic color)
- 550 nm — Broad Mn absorption region (strongest in green direction)
|
| Apatite |
- 512 nm — Rare earth (Dy³⁺) band (moderate; present in some yellow-green apatite)
- 491 nm — Rare earth band (weak; Pr³⁺ in some specimens)
|
| Benitoite |
- 435 nm — Absorption band (moderate; related to Ti content in benitoite)
- 412 nm — Absorption band (weak)
|
| Blue Diamond |
- Broad boron-related absorption tail extending from near-infrared into red visible region (responsible for blue colour in Type IIb; diffuse — no sharp discrete line visible in hand spectroscope)
- No sharp diagnostic lines in visible range — FTIR (2800 cm⁻¹ region) is the definitive boron test; hand spectroscope is not diagnostic for blue diamonds
|
| Cassiterite |
- Strong absorption in the near-UV to violet region, ~350–400 nm (shifts by color variety)
- Brownish-pink varieties show broad band centered ~490 nm
|
| Cat's Eye Chrysoberyl |
- 444 nm — Fe³⁺ absorption band (strong; visible in hand spectroscope — diagnostic for chrysoberyl vs quartz cat's-eye)
- 484–505 nm — Fe³⁺ weaker band region (sometimes visible as a diffuse absorption edge in blue-green)
|
| Chrysoprase |
- Broad Ni²⁺ absorption centered near 630–660 nm in orange-red region (responsible for green colour; no sharp lines — visible as diffuse red-end suppression in hand spectroscope)
- Secondary Ni²⁺ absorption near 380–400 nm in UV-violet region (contributes to overall colour balance)
|
| Citrine |
- 432 nm — Fe³⁺ band (weak; present in natural citrine; distinguishes from glass simulants)
- 420 nm — Fe³⁺ band shoulder (weak; often faint in heat-treated amethyst/citrine)
|
| Clinohumite |
- ~450 nm — general absorption cut-off in the violet (strong; Fe²⁺ in octahedral sites)
- ~540 nm — broad absorption band in the green-yellow region (moderate; Fe²⁺, causes yellow-orange body color)
|
| Grandidierite |
- 480–490 nm — Fe²⁺ absorption doublet (weak to moderate; visible in hand spectroscope in face-up orientation — useful diagnostic for this rare gem)
- Broad Fe²⁺/Fe³⁺ absorption in orange-red region contributing to strong trichroism (dark blue-green / blue / near-colourless)
|
| Green Tourmaline |
|
| Grossular Garnet |
- 407 nm — Fe³⁺ absorption band (weak; present in Fe-bearing grossular varieties)
- 430 nm — Fe³⁺ broad absorption (weak to moderate; varies with iron content)
|
| Hackmanite |
- ~540 nm — F-centre / colour-centre absorption (moderate; responsible for pink-to-purple photochromic colour when UV-activated; present only after UV exposure — fades in daylight)
- No diagnostic bands visible in hand spectroscope on untreated/unactivated material
|
| Jadeite |
- 437 nm — Fe³⁺ band (strong; diagnostic for jadeite; most visible in lavender/white jadeite)
- 630–690 nm — Cr³⁺ bands (strong in imperial green jadeite; chromium doublet-like absorption producing vivid green; absent in Fe-colored greens)
|
| Kornerupine |
- 446 nm — Fe²⁺/Cr³⁺ broad absorption (moderate; chromium-bearing green kornerupine)
- 540 nm — Broad absorption region (moderate; Fe/Cr giving green color in some specimens)
|
| Kyanite |
- 447 nm — Fe²⁺ band (moderate; diagnostic iron band most visible in blue kyanite)
- 433 nm — Fe²⁺ band (weak)
|
| Lapis Lazuli |
- Broad S₃·⁻ radical absorption centered near 600 nm in orange region (responsible for blue colour — diagnostic for lazurite; visible as general orange suppression in hand spectroscope)
- Weak secondary absorption near 400 nm in violet region (S₃·⁻ minor band; not always detectable in hand spectroscope)
|
| Malachite |
- Broad Cu²⁺ absorption centered near 800 nm in near-infrared/deep red region (responsible for green colour; visible as strong red-end suppression in hand spectroscope — no discrete line)
- Absorption cut-off below ~520 nm in blue-violet region (secondary Cu²⁺ band; contributes to green transmission window)
|
| Moldavite |
- Broad Fe²⁺/Fe³⁺ diffuse absorption in blue-violet and near-infrared regions (no sharp lines; two vague bands sometimes noted in blue and orange regions with spectrophotometer — not reliably visible in hand spectroscope)
- No diagnostic discrete lines detectable in hand spectroscope — RI (~1.48–1.50) and tektite surface texture are primary tests
|
| Morganite |
- 572 nm — Mn³⁺ absorption band (strong; primary diagnostic band for morganite's pink color)
- 540 nm — Mn³⁺ band (moderate; secondary manganese band)
|
| Nephrite |
- Diffuse Fe²⁺ absorption near 430–450 nm in violet-blue region (present in dark green nephrite; weak and broad — visible as blue-end suppression rather than a discrete line)
- Broad Fe²⁺/Fe³⁺ absorption in the 600–730 nm orange-red region (responsible in part for green body colour; not a discrete line — most visible as general red-end suppression)
|
| Padparadscha Sapphire |
- 450 nm — Fe²⁺ band (moderate; iron contributing to orange component)
- 693 nm — Cr³⁺ line (weak; chromium contributing to pink component of padparadscha color)
|
| Paraiba Tourmaline |
- 700 nm+ — Cu²⁺ broad absorption tail (strong; copper causes the neon blue-green color; extends into NIR)
- 560 nm — Mn³⁺ broad absorption (strong; manganese absorption band in yellow-green region; reduced or absent after heat treatment)
|
| Prasiolite |
- ~720 nm — broad, weak absorption band in the red (Fe²⁺ intervalence charge transfer; responsible for green hue in heat-treated material)
- ~550 nm — faint Fe³⁺ absorption band (weak; may be present in natural material)
|
| Rhodochrosite |
- Mn²⁺ absorption near 410–425 nm in violet region (Fe²⁺/Mn²⁺ crystal-field band; visible in hand spectroscope in deeply coloured specimens)
- Mn²⁺ absorption near 450–460 nm in blue-violet region (second crystal-field band; may appear as broad absorption shoulder)
|
| Rhodonite |
- Mn²⁺ absorption near 410 nm in violet region (crystal-field band; analogous to rhodochrosite)
- Mn²⁺ absorption near 503 nm in blue-green region (second Mn²⁺ band; visible in deeply coloured specimens as a diffuse band)
|
| Rubellite |
- 524 nm — Mn³⁺ absorption band (strong; primary diagnostic band for rubellite's red-pink color)
- 453 nm — Mn³⁺ band (moderate; short wavelength manganese band)
|
| Scapolite |
- 663 nm — Mn²⁺ band (moderate; present in purple/violet scapolite; manganese coloration)
- 652 nm — Mn²⁺ band (moderate; paired with 663nm)
|
| Serpentine |
- ~450 nm — weak, broad absorption band in the blue-violet (Fe³⁺ from oxidized structural Fe²⁺)
- ~570 nm — weak, broad absorption band in the yellow-green (Fe³⁺; contributes to green body color)
|
| Star Diopside |
- 505 nm — Fe²⁺/Fe³⁺ absorption band (moderate; iron absorption in diopside)
- 508 nm — Fe²⁺ band (moderate; diagnostic for iron-bearing diopside)
|
| Star Sapphire |
- 450 nm — Fe²⁺/Fe³⁺ iron band (moderate; same as blue sapphire; diagnostic for blue star sapphire)
- 460 nm — Fe²⁺ band (moderate)
|
| Synthetic Color-Change Corundum |
- 693 nm — Cr³⁺ line (strong; vanadium and chromium dopants used to create blue-to-red color change)
- 450 nm — Fe²⁺/V³⁺ band (strong; causes absorption of visible blue-green in combination with Cr/V)
|
| Taaffeite |
- Iron-bearing specimens may show absorption similar to iron-bearing spinel (broad Fe²⁺ band 400–590 nm)
- Chromium-rich specimens show absorption band ~550 nm
|
| Thulite |
- Mn³⁺ absorption near 455 nm in violet-blue region (crystal-field band; visible in hand spectroscope in deeply coloured specimens)
- Mn³⁺ absorption near 560–580 nm in yellow-green region (second Mn³⁺ band; responsible for pink colour by subtracting green from white light)
|
| Variscite |
- Cr³⁺ absorption doublet with bands near 645 nm and 690 nm in orange-red region (visible in hand spectroscope — similar pattern to emerald; supports Cr³⁺ as chromophore)
- Broad Cr³⁺ absorption near 430–450 nm in violet region (responsible for absorbing violet, contributing to green transmission)
|
| Watermelon Tourmaline |
- Variable FE in green zone
- MN in pink zone
|
| Yellow Sapphire |
- 450 nm — Fe²⁺ band (weak to moderate; Fe-colored yellow sapphire may show this band; absent in Be-diffused material)
- 460 nm — Fe²⁺ band (weak; secondary iron band)
|
| Ametrine |
- Broad absorption band centered ~540 nm (amethyst zones, Fe³⁺/Fe⁴⁺ charge transfer)
|
| Aventurine |
- Chromium (Cr³⁺) absorption from fuchsite inclusions: bands ~450 nm and ~600–680 nm
|
| Bloodstone |
- Broad Fe absorption; diffuse bands in the red ~630–670 nm region from iron oxide/hematite inclusions
|
| Carnelian |
- Broad diffuse iron absorption bands centered near 580 nm, 610 nm, 630 nm, 640 nm, and 665 nm
|
| Chrysoberyl |
- 444 nm — Fe³⁺ band (moderate; most visible in yellow-green chrysoberyl; iron absorption in blue-violet region)
|
| Chrysocolla |
- Broad Cu²⁺ absorption centered near 700–800 nm in orange-red region (responsible for blue-green colour transmission; visible as general red suppression rather than a discrete line)
|
| Cinnabar |
- ~600 nm — strong absorption edge; blue-violet and green regions essentially cut off (band-gap absorption in HgS causes intense red/vermilion color)
|
| Color-Change Garnet |
- Three broad bands across orange-yellow-green — garnet trio
|
| Cuprite |
- ~450–530 nm — broad, strong absorption across blue to green-yellow (band-gap and charge-transfer absorption in Cu₂O; causes deep red color)
|
| Diamond |
- Sharp line in the violet (~415nm) — Cape diamond line
|
| Hauyne |
- Broad S₃·⁻ radical absorption centered near 595–620 nm in orange region (responsible for intense blue colour; diffuse — visible as general orange-red suppression in hand spectroscope rather than a discrete line)
|
| Labradorite |
- ~418 nm and ~448 nm — two weak, diffuse absorption bands in the violet-blue (weak; Fe³⁺ in tetrahedral Si/Al sites; often too faint for hand spectroscope)
|
| Larimar |
- Broad absorption centered near 630 nm in orange region (attributed to Cu²⁺ and/or Fe²⁺–Fe³⁺ intervalence charge transfer — responsible for blue-green colour; no sharp lines visible in hand spectroscope)
|
| Malaya / Umbalite Garnet |
- Broad bands in the green (~524nm) and blue-violet (~453nm) — manganese
|
| Moissanite |
- 419 nm — Diagnostic absorption band for synthetic moissanite (SiC)
|
| Prehnite |
- ~438 nm — weak absorption band in the violet-blue (Fe³⁺ in octahedral Al sites; causes pale green color)
|
| Red Beryl |
|
| Rose Quartz |
- ~500 nm — weak, broad absorption band (Fe-Ti intervalence charge transfer in fibrous inclusions; causes pink color)
|
| Sodalite |
- ~675 nm — step-shaped absorption in the red (S²⁻/S³⁻ sulfide cluster electronic transition; contributes to royal blue color)
|
| Star Garnet |
- Three broad bands across orange-yellow-green — garnet trio
|
| Sugilite |
- Broad Mn³⁺ absorption envelope centered near 560 nm spanning approximately 500–700 nm (responsible for violet-purple colour; visible in hand spectroscope as broad green-yellow suppression)
|
| Sunstone |
- ~560–590 nm — broad absorption band (localized surface plasmon resonance of copper nanoparticle inclusions; causes red-orange to green colors in Oregon sunstone)
|
| Tourmaline |
- Variable by color — Fe²⁺ bands in green/blue varieties; Mn³⁺ bands in pink/red; Cr³⁺ bands in chrome tourmaline; Cu²⁺ bands in Paraiba
|
| White Sapphire |
- No strong diagnostic bands — white/colorless sapphire typically shows clean spectrum (no Fe or Cr color centers in colorless corundum)
|
| YAG |
- No diagnostic absorption bands in colorless YAG — clean featureless spectrum (undoped YAG has no chromophores)
- Colored YAG (doped): Er³⁺ at 450nm+, Nd³⁺ at 578nm, Cr³⁺ at 689nm depending on dopant used
|
| Agate |
- No diagnostic absorption bands in the visible spectrum
|
| Amber |
- No diagnostic absorption bands in the visible spectrum
|
| Black Opal |
- No diagnostic absorption bands in the visible spectrum
|
| Black Spinel |
- No diagnostic visible bands — black spinel shows general absorption; Fe-Ti charge transfer causes near-complete absorption throughout visible spectrum in opaque specimens
|
| Chalcedony |
- No diagnostic absorption bands in the visible spectrum
|
| Charoite |
- No diagnostic absorption bands in the visible spectrum
|
| Coral |
- No diagnostic absorption bands in the visible spectrum
|
| Danburite |
- No diagnostic absorption bands — danburite shows a clean featureless spectrum; colorless to pale yellow specimens are essentially transparent across the visible range
|
| Fire Opal |
- No diagnostic absorption bands in the visible spectrum
|
| Fluorite |
- No diagnostic absorption bands — spectrum generally clean (fluorite is typically featureless in the visible range)
|
| Goshenite |
- No diagnostic absorption bands in the visible spectrum
|
| Hawk's Eye |
- No diagnostic absorption bands in the visible spectrum (opaque/chatoyant; residual Fe absorption from crocidolite/riebeckite fibers not resolvable in hand spectroscope)
|
| Hematite |
- No diagnostic absorption bands visible in the visible spectrum with a hand spectroscope (opaque metallic material; broad Fe₂O₃ absorption throughout visible range)
|
| Howlite |
- No diagnostic absorption bands in the visible spectrum
|
| Ivory |
- No diagnostic absorption bands in the visible spectrum
|
| Jet |
- No diagnostic absorption bands in the visible spectrum (opaque black organic material absorbs all visible wavelengths)
|
| Moonstone |
- No diagnostic absorption bands in the visible spectrum
|
| Obsidian |
- No diagnostic absorption bands in the visible spectrum
|
| Onyx |
- No diagnostic absorption bands in the visible spectrum (opaque; black color from carbonized inclusions or dye treatment)
|
| Opal |
- No diagnostic absorption bands in the visible spectrum
|
| Pearl |
- No diagnostic absorption bands in the visible spectrum (hand spectroscope)
|
| Phenakite |
- No diagnostic absorption bands in the visible spectrum
|
| Pietersite |
- No diagnostic absorption bands in the visible spectrum (opaque/chatoyant; Fe absorption from hematite/goethite inclusions diffuse and not resolvable)
|
| Rainbow Moonstone |
- No diagnostic absorption bands in the visible spectrum
|
| Rock Crystal |
- No diagnostic absorption bands in the visible spectrum
|
| Smoky Quartz |
- No diagnostic visible bands — spectrum featureless (color from Al/H color centers; no sharp spectroscope lines visible in standard gemological spectroscope)
|
| Tiger's Eye |
- No diagnostic absorption bands in the visible spectrum (opaque/chatoyant; diffuse Fe³⁺/limonite absorption not resolvable into lines)
|
| Topaz |
- No diagnostic absorption bands — spectrum generally featureless (most topaz colors arise from color centers or trace elements without sharp spectroscope absorption)
|