orthorhombic Synthetic synthetic chrysoberyl

Flux-Grown Alexandrite (Crystal)

Formula 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 +

Physical Properties

Crystal System: orthorhombic
Hardness (Mohs): None
Specific Gravity: 3.7
Cleavage: Distinct {110} in two directions
Fracture: Conchoidal
Lustre: Vitreous

Optical Properties

Refractive Index: 1.746
Birefringence: 0.009-0.010
Optical Character: Biaxial +
Dispersion: 0.015
Pleochroism: strong: Green (daylight/fluorescent) / Red to purplish-red (incandescent)
Fluorescence: Moderate red (LW UV)

Origin & Identification

Origin: Synthetic
Growth Method: Flux (molybdate Or Vanadium-based Flux Solvent In Platinum Crucible; Slow-cooling Crystallisation)
Manufacturer: Chatham Created Gems (San Francisco, USA); Creative Crystals Inc. (USA); Russian laboratory production
First Produced: 1964
Diagnostic Features: Flux 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

Characteristics

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).