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Extracts of Articles
Amethyst The art of lapidary is to place the color correctly in
order to make homogeneous the tone of the cut stone. The
distribution of the color in a cut stone is observed simply by
immersing it in water contained in a transparent container and
colourless. Corundum Corundum is composed of pure alumina; its
colouring is due to metallic oxide traces or inclusions. Gems
are generally found in alluvium, but come either from basaltic
slag, or from metamorphosed limestone.
Tourmaline Coloured tourmalines are related to sodolithic
pegmatite. One distinguishes two principal types of tourmalines:
the hexagonal type and the triangular one.
The Mine of Anjanabonoina, located in the high plateaus,
produced rubellites, green tourmalines, and a variety of rare
stones. Garnet
The Besafotra river carry the spessartites on several
kilometers from their source, doubtless a sodolitic pegmatite.
Tanety "grounds bordering the river," are also the object of the
orange garnet's fever. Malaya Garnet Discovery This marvellous
chromium-spessartite garnet from Madagascar was discovered in
its bedrock in 1996. This discovery remains exceptional by the
quality of its product and also by the fact that it was the
second deposit in the world to deliver this type of Malaya
garnet. Crystalline Systems 7 systems of crystallization: There
are 32 possibilities of combinations of the elements of
symmetry. All the geometrical operations which cause a
repetition of the pattern are called operations of symmetry.
Cutting Styles
Table, Crown, Girdle, Pavilion, Culet. Fancy Styles Back to Top
Shield Cut, Trillant Cut.
Cutting Characteristics When a stone is cut according to good
proportions, the light is reflected from one facet to another
and arises by the top.
Gemology
Microscopes: the binocular one, i.e. to double objective is best
adapted for gemology. The microscope is of first importance in
the detection of counterfeits. Indeed, the study of inclusions
which the stone can contain is a practical means to identify the
gems while explaining to a certain extent the conditions under
which they were formed in nature. Size & Weight Back to Top
Sapphire, Ruby, Emerald. Madagascar gem safari
At the time of the great dryness in the south, sapphire samples
are found on the ground, several centuries after their first
discovery. Actually, one of the most beautiful quality in the
world is just leaving ground. Rare Stones Safari
The Yellow orthoclase from Itrongay, was found in eluvium, but
comes from a pegmatite with diopside of a very special type,
which presents the single characteristic to be made of
transparent minerals only.
About Ilakak
It is in the accesses of the downwards brook named Ilakaka that
the first sapphires were found in 1998. The excavations follow
the gravel deposits which the Madagascans call lalam' bato, (the
way of stones.)
The essential characteristic of the Isalo formations is their
main constitution of soft sandstones, very permeable, badly
cemented which disaggregate easily on surfaces by giving thick
siliceous sand coverings. Sakalama This sapphire of natural
color, therefore untreated was found in alluvium in the
sandstones. This is why it does not have any more its original
shape. The first deposits consist of conglomerates, gravels and
sands, One finds there elements of rocks and minerals: quartz,
feldspars, micas, zircons, tourmalines, ilmenites, magnetite,
monazite, rutile, chrysoberyls, corundum. Andranondambo Area The
occurrences of the Andranondambo area were industrially
exploited since 1993 and have been almost abandoned few years
later. Actually, it is very difficult to exploit sapphire direct
in the mother rock, because the corundum is not concentrated
enough. This sapphire was sold as a Kashmir Sapphire by some
dealers on the international market.
Pakistan Gem Safari The Northern areas conceals treasures, such
of rubies, emeralds, sapphires, aquamarines, topazes,
tourmalines etc. This is at the occasion of one of our visits in
the valley, that some children tolled us that they found some
fragments of emerald in the Swat river. Gem Adventure (novel)
The plane landed early – something extremely rare on the AirMad
line serving Tananarive. Mrs. Nory was standing on the airport's
tarmac, right next to a gendarme. She welcomed her daughter Tina
coming back from Belgium. © 1987 - 2004 gggems.com All rights
reserved.
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