J. C. (Hanco) Zwaan

ABSTRACT: Demantoid garnets from Antetezambato, northern Madagascar, contain a cha

teristic inclusion suite typical of a skarn occurrence. Unlike demantoid from the classic depo

in the Ural Mountains, Russia, and from other serpentinite-related occurrences, the stones fi

Madagascar do not contain 'horsetail' inclusions, but instead host groups of small, rounded diop:

grains, fluorapatite, dolomite, calcite, quartz, pyrite and wollastonite, as well as rare native bism

Partially healed fissures contain two-phase fluid inclusions (with H,O and a gas bubble) of vary

salinity. Negative crystals, commonly large and empty, sometimes also contain H,O. Pronoun

growth features and parallel hollow tubes are also present. Demantoid from Namibia likewise hi

skarn origin and shows some similar internal features, as well as some that are different, such as

common presence of fluorapatite and small multiphase fluid inclusions, along with the absenc

large negative crystals and native bismuth. A review of previously advocated methods for geograt

origin determination of demantoid based on chemical fingerprinting alone shows that this techni

is applicable only to stones with a nearly pure andradite composition when differentiating Malag

and Namibian localities. In such cases, elevated traces of Mn are indicative of a Namibian origi

The Journal of Gemmology, 38(1), 2022, pp. 64-79, https://doi.org/10.15506/JoG.2022.38.1.64

• 2022 Gem-A (The Gemmological Association of Great Britain)

merald, the green chromium-bearing variety

of beryl (Be;Al,Si,O¡8), has been one of the

most sought-after gem materials throughout

history. Since the 17th century, emeralds

from Colombia have gained the highest reputation and

market importance, but other sources have also emerged

in recent decades, such as Zambia (e.g. Kafubu),

Madagascar (e.g. Mananjary) and Ethiopia (Shakiso)

in Africa, as well as Pakistan (Swat Valley), Afghanistan

(Panjshir [Panjsher] Valley) and China (Davdar in the

Xinjiang Uyghur Autonomous Region) in Asia. Stones

from the Panjshir Valley in Afghanistan are commonly

described as resembling Colombian emeralds in terms

of colour, quality and even inclusion features (Bowersox

et al. 1991; Schwarz & Pardieu 2009). Their reputation

is underscored by the fact that a 10 ct Afghan emerald

was sold at auction in 2015 for USD2.275 million (Chris-

tie's 201 5) -equivalent to the highest recorded per-carat

price for any emerald from a non-Colombian locality.

The Swiss Gemmological Institute SSEF regularly

receives emeralds from Afghanistan for testing, quite

often in impressive layouts and settings. In the past,

determining their geographic origin was in most cases

quite straightforward. However, in early 2017 this

changed, and since then we have analysed more than

100 samples of an apparently new type of emerald from

the Panjshir Valley in Afghanistan. (Hereafter in this

article these stones will be referred to as 'Panjshir type

I' emeralds.) They have been submitted to SSEF by