Organic gemstones

1. ORGANIC GEMS
PEARL
AMBER
CORAL
IVORY

2. ORGANIC GEMS
PEARL: It is made up of concentric layers of organic material
called conchiolin (C32H48O11) and platelets of Aragonite (CaCO3).
Conchiolin acts as cementing material. Conchiolin concentration is
higher between layers. Individual layers are known as NACRE or
mother-of-pearl (m-o-p)
Pearl contains 82-86% Aragonite
10-14% Conchiolin
1-4% water
Natural Pearl: Pearls grown around an irritant or a foreign body that
accidentally enters the shell of a muscle in nature.
Cultured Pearl:Pearl grown in mussels (usually cultivated by man) with
deliberately introduced large nucleus as irritant, usually a round bead
cut from the fresh water (m-o-p) shell. Few molluscan species are
capable of producing pearl eg: genus pictada radiata-
Marine species:pictada radiata-Gulf of Mannar, Persian gulf and red
sea.
Largest pearl-Phillipines-6.37 kgs, 14cm across

3. PROPERTIES
• Hardness of pearl generally varies from 2.5-3.5
• Refractive index of pearls are not much
important
• Birefringence is extremely high
• Color is milky white with a tinge of yellow,green,
bluishgrey and pink. Often it may be distinctly
pink,bronzeyellow and even black
• Pearls are measured in terms of grains. 1
grain=.025 carat or 50mg
• Most important properties is it’s pearly lustre or
sheen

4. A BLACK PEARL AND A SHELL OF THE BLACK-LIPPED PEARL OYSTER
WHITE PEARL

5. AMBERAMBER
• AmberAmber is fossilized tree resin (not sap), which has beenis fossilized tree resin (not sap), which has been
appreciated for its color and natural beauty since Neolithicappreciated for its color and natural beauty since Neolithic
times.times. Much valued from antiquity to the present as aMuch valued from antiquity to the present as a
gemstone, amber is made into a variety of decorative objects.gemstone, amber is made into a variety of decorative objects.
Amber is used as an ingredient in perfumes, as a healingAmber is used as an ingredient in perfumes, as a healing
agent in folk medicine, and as jewelry. There are five classesagent in folk medicine, and as jewelry. There are five classes
of amber, defined on the basis of their chemical constituents.of amber, defined on the basis of their chemical constituents.
Because it originates as a soft, sticky tree resin, amberBecause it originates as a soft, sticky tree resin, amber
sometimes contains animal and plant material as inclusions.sometimes contains animal and plant material as inclusions.
Amber occurring in coal seams is also calledAmber occurring in coal seams is also called resinite.resinite.

6. AMBER: This is a fossil resin exuded by ancient pine trees
and subsequently buried in sediments after transport.
Composition of Amber is C10H16O with H2S
Age: Carboniferous (300 m.y) to Pleistocene (1.5 m.y)
Locality: Tertiary Lignite deposits in Kutch and Rajpipla in
Gujarath state

7. AMBER

8. CORAL: It is an invertebrate animal beloging to the
phyllum Cnidaria. These tiny animals live in cavities built
in branching skeleton made up of CaCO3. It can grow up
to 1mtr.
Locality: Deep south east coast (Rameshswaram) and
Jollybuoy islands in Andaman

9. •CORALS are marine invertibrates
in class Anthozoa of phylum Cnidaria typically living in
compact colonies of many identical individual "polyps".
The group includes the important reef builders that
inhabit tropical oceans and secrete calcium carbonate to
form a hard skeleton.
• A coral "head" is a colony of myriad genetically identical
polyps. Each polyp is a spineless animal typically only a
few millimeters in diameter and a few centimeters in
length. A set of tentacles surround a central mouth
opening. An exoskeleton is excreted near the base. Over
many generations, the colony thus creates a large
skeleton that is characteristic of the species. Individual
heads grow by asexual reproduction of polyps.

10. CORALS

11. IVORYIVORY
• Ivory is one of the most well known materials that are usedIvory is one of the most well known materials that are used
in high quality precious jewelry. It should be noted that Ivoryin high quality precious jewelry. It should be noted that Ivory
is not a gemstone or a mineral from rock, it is an organicis not a gemstone or a mineral from rock, it is an organic
mineral created by certain mammals with specific types ofmineral created by certain mammals with specific types of
characteristics.characteristics.
•Ivory is created by a mammal that grows Ivory as their teethIvory is created by a mammal that grows Ivory as their teeth
and tusks. A tusk is a general term for any teeth that growsand tusks. A tusk is a general term for any teeth that grows
outside the mouth area. Some of the animals that produceoutside the mouth area. Some of the animals that produce
Ivory are elephants, hippos, walrus’s, elks, wart hogs andIvory are elephants, hippos, walrus’s, elks, wart hogs and
even marine mammals.even marine mammals.
•Ivory usually comes in two colors, white and whitish yellow,Ivory usually comes in two colors, white and whitish yellow,
many people usually call it off white. The whiter the Ivory,many people usually call it off white. The whiter the Ivory,
usually the higher the priceusually the higher the price..

13. PROPERTIES
• Hardnress-2-3
• Specific gravity-1.7-2
• RI-1.54
• Lustre-greasy
• Fracture-hackly
• Specific gravity of elephant ivory-1.75