COLOR CHANGE GARNET

Color-change garnets are a variety of garnet formed by the mixture of 2 garnet species. Garnets are nesosilicate minerals that constitute an isomorphous series, that is, their crystal structure is basically the same (X₃Y₂(SiO₃)₄), but they differ in their chemical compositions. There are over 20 different garnet species, but only 6 of them are considered to be gem-worthy, some of which include a few varieties. These species are pyrope, almandine, spessartite, grossularite, andradite and uvarovite. Color-change garnets are typically a result of a pyrope-spessartite mix, although many may also contain traces of grossularite or almandine.

LEGEND AND LORE

Garnets in every variety are birthstones of the month of January. It is traditionally given on the 2nd and 6th wedding anniversaries.

GARNET, COLOR CHANGE COLORS

Color-change garnets usually display a distinct color change between various intensities of very slightly bluish Green (15) to very strongly greenish Blue (19) under fluorescent light and Purple-Red (29) to strongly purplish Red (30) under incandescent light.

GARNET, COLOR CHANGE SOURCES

Color-change garnets are found in Tanzania, Madagascar, Sri Lanka and USA.

PHYSICAL PROPERTIES

Variety: Color Change
Species/Series: Garnet, Pyrope and Spessartite mixture
Chemical Composition: Magnesium manganese aluminum nesosilicate ([Mg₃+Mn₃]Al₂(SiO₃)₄)
Crystal System: Isometric (Cubic)
Color: slightly bluish Green to very strongly greenish Blue under fluorescent light and Purple-Red to strongly purplish Red under incandescent light
Hardness: 7.0 to 7.5
Refractive Index: 1.73 to 1.81
Specific Gravity: 3.78 to 3.85

For information on other Garnet varieties, select Garnet in the Gem Type field.

Properties: RI 1.76 HARDNESS 7-7.5 SPECIFIC GRAVITY 3.78-3.85 SPECIES-PYROPE/SPESSARTITE OPTIC CHARACTER-SR PHENOMENA-COLOR CHANGE
Reactions: Ultrasonic: Usually safe Steamer: Never Heat: Fair-poor;temperature changes may cause fracturing
Major Sources: East Africa, Madagascar
Grading Information
Enhancement Code: NONE
Specific Gravity: 3.78

Source: