orthorhombic Synthetic synthetic chrysoberyl

Flux-Grown Alexandrite (Crystal)

BeAl2O4:Cr

Crystal Structure

CDL Notation

 #! Species: Flux-Grown Alexandrite
#! System: Orthorhombic (mmm)
#! Habit: Tabular from flux growth
orthorhombic[mmm]:{110}@1.0 + {010}@0.7 + {001}@0.4

Crystal System orthorhombic

Point Group mmm

Crystal Forms (3)

{110} {010} {001}

Quick Facts

Hardness

None

Specific Gravity

3.7

Refractive Index

1.746

Optical Character

Biaxial +

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Physical Properties

Crystal Systemorthorhombic

Hardness (Mohs)None

Specific Gravity3.7

CleavageDistinct {110} in two directions

FractureConchoidal

LustreVitreous

Optical Properties

Refractive Index1.746

Birefringence0.009-0.010

Optical CharacterBiaxial +

Dispersion0.015

Pleochroismstrong: Green (daylight/fluorescent) / Red to purplish-red (incandescent)

FluorescenceModerate red (LW UV)

Origin & Identification

OriginSynthetic

Growth MethodFlux (molybdate Or Vanadium-based Flux Solvent In Platinum Crucible; Slow-cooling Crystallisation)

ManufacturerChatham Created Gems (San Francisco, USA); Creative Crystals Inc. (USA); Russian laboratory production

First Produced1964

Diagnostic FeaturesFlux fingerprints (wispy veils following crystal growth sector boundaries; smoky diffuse appearance — unlike natural fingerprints which follow healed fracture planes); platinum platelets (flat hexagonal to irregular Pt metal from Pt crucible; bright mirror-like under dark-field — highly diagnostic); flux feather inclusions (irregular solidified flux masses); absence of twinning planes (natural Russian alexandrite shows polysynthetic twinning); absence of natural inclusions (no negative crystals, no two-phase natural fluid inclusions); Mo or V trace contamination from flux detectable by EDXRF

Colours

Green (daylight)Red to purplish-red (incandescent)

Common Inclusions

Flux fingerprints (wispy veils)Platinum platelets (Pt from crucible)Flux feather inclusions

Notes

Note: existing synthetic-alexandrite-czochralski.yaml already in DB; this file covers the flux-grown variety only (Chatham/Creative Crystals). Do not confuse with Czochralski. Schmetzer, Peretti, Medenbach & Bernhardt 1996, Gems & Gemology 32(3):186 (DOI 10.5741/gems.32.3.186) [VERIFIED]: Russian flux-grown alexandrite diagnostics. Platinum platelets are definitive — absent in all natural alexandrite. Flux veils differ from natural fingerprints by their growth-sector relationship. EDXRF: very low trace elements; Mo or V trace from flux; no significant Fe; no Ga. Distinguishes from hydrothermal (chevron zoning + nail-head spicules) and Czochralski (curved striae + iridium inclusions).