© 2004 ... All rights ... Extracts of Articles Amethyst Data The art of lapidary is to place the color ... in order to make ... the tone of the cut stone. The ...
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Extracts of Articles
Amethyst Data
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 Data
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 Data
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 Data
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.
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