CORAL

INTRODUCTION:- These tiny creatures live in colonies which form branching structures as they grow, coral is composed mainly of calcium carbonate in the form of fiber calcite eventually forming coral reefs and atolls.The height of the branches is in the general range 8 - 10 inches; the branches are up to 2.5 inches. We found different types of coral in colours such as red, orange, pink, white, blue & black. White, black and golden corals are formed from a material known as conchioline.  All corals have a delicate graining of stripes as spots in their skeletal structure.

Coral is found in many verities and colours. The most coral used in Jewellery is  CORRALLIUM RUBRUM or CORRALLIUM NOBILE. Most of the coral used since antiquity as an ornamental material comes from the CALCAREOUS SKELETONS.

The most famous of these organisms is corrallium rubrum, a white coral oculinacea vaseuclosa has been fashioned for ornamentation. 

Romans believed Red Mediterranean coral magical and medicinal properties, and Roman children wore coral necklaces as protection from dangers.

Black coral is also known as akbar or "King's Coral" and blue coral is also called Akori. Red, Pink, White, black and golden corals are formed from a material known as conchiolin.

DEPOSITS:-

Most coral types exist in warm water from 20 - 1000 feet deep with the best equality coral found from 100 - 160 feet. Red and pink corals exits along the Mediterranean coasts of Italy, France and Africa. Black  and golden coral occur off Australia, Hawaii and the west indies.  Shining black coral comes from the Indian ocean, while pink, red and white coral comes from Japan. Other deposites are found in the Red Sea and off the coasts of Algeris, Tunisia and Malaysia.

PROPERTIES:-

The various properties of Emerald are:-

Species                           :        CORAL

Variety                             :         Coral

Chemical Composition    :        Organic substance with CaCO₃  along with about 3% of MgCO₃

Crystal System                :        Organic material, no particular crystal system

Color                              :        Light Pink, Dark red, Orange, Black Coral is conchiolin. After bleaching produces a golden colour.

Cause of Color               :        Iron, Magnesium

Transparency                 :        Semi translucent to opaque.

Luster                             :        Waxy

Hardness                        :        3.5

Specific Gravity              :        2.6  to 2.7

Pleochroism                   :        None

R.I. Range                       :        1.486  – 1.658 (1.55 Spot)

Optic Sign                       :        None

Birefringence                 :        0.172

Dispersion                      :        0.017

INCLUSION:-

There are inclusion types found in Coral :-

Wood grain effect, Grooves, Pits or cavity and Striations.