Color Change Sapphire | Gemopedia

While color change sapphires come from a variety of locations, the gem gravels of Tanzania are the main source. Color change sapphires present gem lovers with an opportunity to own the rare and stunning color change effect in a gem other than alexandrite, garnet, spinel, tourmaline or diaspore. While the colors tend to vary depending on locale, in general they change from blue to purple. You can observe color change in this gem by viewing it interchangeably in natural and incandescent light.
Colors
Pink-Brown Through Brownish Pink, Purple Changing To Yellowish Brown, Grayish Violet, Grayish Blue, Green

Color Change Sapphire Classification

Common Name

Color Change Sapphire

Species

Corundum

Variety

Color Change Sapphire

Colors

Pink-Brown Through Brownish Pink, Purple Changing To Yellowish Brown, Grayish Violet, Grayish Blue, Green

Alternate Names

Gemstone Groups

Key Separations

RI, birefringence, magnification and color change

Comments

Will have a spectra similar to ruby and pink sapphire.

Color Change Sapphire Optical Properties

Transparency

Transparent - Semitranslucent

Refractive Index

1.762-1.77
Tolerance:(+0.009/-0.005)

Birefringence

0.008-0.01

Optic Character

Uniaxial

Optic Sign

Negative

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert
LWUV: Inert

CCF Reaction

Pleochroism

Dichroic, varies with bodycolor

Dispersion

Strength: weak fire Value: 0.018

Comments

Color Change Sapphire Chemistry & Crystallography

Chemical Name

aluminum oxide

Chemical Formula

Al2O3

Synthesis

Crystal System

Trigonal

Classification

Oxide

Nature

Natural

Crystallinity

Crystalline

Comments

Color Change Sapphire Characteristic Physical Properties

Hardness

9

Streak

White

Specific Gravity

4.1-3.95 Typical:4

Toughness

Excellent

Inclusions

This stone has a type II clarity. Color change sapphire sometimes have silk composed of rutile needles, dark brown crystals, boehmite or zircon crystals. Stones might have fingerprint or 2-phase inclusions. Hexagonal growth and strong color zoning are possible in some stones. Untreated stones will usually have inclusions intact. Heat treated stones will have fracture halos or snowballs around crystal inclusions(untreated stones from magmatic areas might also show these characteristics). Silk will be broken and might show sintered areas especially around the girdle.

Luster

SubAdamantine

Stability

Very Good

Fracture

Conchoidal

Cleavage

None

Comments

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