Nata Heng Schluessel, GG logo Roland Schluessel, FGA

Garnet

Mandarin Garnet

91211

WHAT IS A GEM GARNET?

APPEARANCE:

The key for judging Garnets relies in avoiding stones with a brownish tone and Stones that are too dark, lack transparency, are heavily included or appear “sleepy” are considered of lower quality.

Color = All except blue.
Pleochroism = None.
Transparency = Transparent.
Brilliancy = Very high; can be masked by an excessively strong color saturation.
Clarity = Gem-quality stones are expected to be “eye-clean”.
Phenomena = Asterism in some Garnet types (e.g. Almandine Garnet).

PHYSICAL PROPERTIES:10

Hardness = 7 to 7 ½.
Toughness = Fair to good.
Cleavage = None; sometimes distinct parting.
Refractive Index = Varies between 1.714 and 1.888 according to type of Garnet.
Specific Gravity = Varies between 3.61 and 4.05 according to type of Garnet.

CLEANING METHODS:

Ultrasonic = Usually safe but risky, if the stone contains liquid inclusions. Grossularite and Spessartite contain mainly liquid inclusions.
Steamer = Never use a Steamer with Garnet.
Warm soapy water = Safe.

STABILITY:

Reaction to heat = Abrupt temperature changes are likely to cause fracturing.
Reaction to chemicals = Slowly/slightly attacked by hydrofluoric acid.

MAJOR SOURCES:

31Tsavorite = Tanzania.
Mandarin Garnet = Nigeria, Namibia.
Rhodolite = Tanzania, Sri Lanka.
Green Grossularite = Mali, Tanzania.
Malaia Garnet (Umbalite) = Tanzania.
Demantoide = Russia, Pakistan, Namibia.

ENHANCEMENTS:

None.

IMITATIONS:

Glass, assembled stones (e.g. doublets and triplets) and other gemstones of lower value.

Tsavorite Garnet

13 14
In East-Africa, on our way to the Tsavorite Garnet and Tanzanite gem deposits. Tsavorite Garnet and Tanzanite are found in Merelani, Tanzania.

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From the gemological point of view, the Garnet is one of the most interesting gemstone families because they possess the ability to combine their chemical composition between each other. For example, the combination between the dark red Pyrope and the brownish red Almandite results in the attractive purplish red Rhodolite.

Their potential for use in color stone jewelry increased dramatically since the 1960s with the discoveries of many new Garnet types: Tsavorite, Malaia Garnet, Mandarin Garnet, various types of Grossularite and new sources for Demantoid.

MAIN GARNET VARIETIES FOR USE IN VALUABLE JEWELRY:

Tsavorite (Chrome Grossularite) = Emerald green.
Mandarin Garnet (Spessartite) = Orange.
Rhodolite = Purplish red.
Green Grossularite = Yellowish green to brownish green.
Malaia Garnet (Umbalite) = Reddish orange to brownish orange.
Demantoide (Chrome Andradite) = Green; resembles a green Diamond.

 

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