diamond as a gemstone

SEMINAR ON DIAMOND

By:-Saurabh Kumar Mishra

Contents• Introduction• Classification of Diamond• Physical Properties of Diamond• Optical Properties of Diamond• Distinguish Properties • Diamond Cutting• Genesis of Diamond• Diamond in India• World occurrence of Diamond• Conclusion• References

Introduction• Diamond is a rare, naturally-occurring

gemstone composed of carbon.

IntroductionDiamond is a rare, naturally-occurring

gemstone composed of carbon.Each carbon atom in a diamond is

surrounded by four other carbon atoms and connected to them by strong covalent bonds.

• It is chemically resistant and it is the hardest known natural substance.

Classification of Diamond

Diamond

Type- I Consist of nitrogen atoms in varying proportion

Type- II

Classification of Diamond

Diamond

Type- I

Type- Ia

Type- Ib

Nitrogen content 0.1%i.e. 1:1000 atoms

Nitrogen content very

lessi.e. 1:1.000,000 atoms

Type- II

Classification of Diamond

Diamond

Type- I

Type- Ia

Type- Ib

Type- IaA

Type- IaB

• Wherein along with

the platelets.• nitrogen occurs as pairs of atoms.

• Nitrogen forms larger clusters • containing an even number of atoms.

Type- II

Classification of Diamond

Diamond

Type- I

Type- II

Type- Ia

Type- Ib

Type- IaA

Type- IaB

Do not have significant amount of nitrogen.Consist of boron in the lattice.Thermal conductivity is about three times that of type I.

Classification of Diamond

Diamond

Type- I

Type- II

Type- Ia

Type- Ib

Type- IIa

Type- IaA

Type- IaB

Paucity of both nitrogen

and boron.Enhanced optical and thermal properties.Type- IIb

Classification of Diamond

Diamond

Type- I

Type- II

Type- Ia

Type- Ib

Type- IIa

Type- IIb

Type- IaA

Type- IaB

Presence of boron atoms in solid solution.Extremely rare in nature.

Classification of Diamond

Diamond

Type- I

Type- II

Type- Ia

Type- Ib

Type- IIa

Type- IIb

Type- IaA

Type- IaB

Physical Properties of Diamond

Cleavage Perfect 4 Set octahedral

Colour Colourless, White, Gray, Black, Blue

Specific Gravity 3.5 - 3.53, Average = 3.51

Diaphaneity Transparent to Sub-transparent to translucent

Fracture Conchoidal

Habit  well-formed crystals showing good external form

Hardness 10

Luster Adamantine

Streak colorless

Chemical Formula C

Optical Properties of Diamond

Type Isotropic

Refractive Index 2.418

Birefringence None

Pleochroism None

Dispersion High, 0.044

Surface Relief  Moderate

DISTIGUISHING PROPERTIES OF NATURAL DIAMOND AND SYNTHETIC DIAMOND (CUBIC ZIRCONIA)

NATURAL DIAMOND

Specific gravity is 3.52

High thermal conductivity

Transparent to X-rays

SYNTHETIC VARIETY (CUBIC ZIRCONIA)

Here it is 4.55 to 7.05 more heavier than natural ones

Low thermal conductivity

Less transparent and leaves a marked impression

Breath test:- the mist created by breathing on gem diamond clears faster than other stimulants.

Sticky test:- diamond sticks to fingers better than other stones which fall when attempted to pick up by moistened fingers.

Droplet test:- a drop of water on a thoroughly cleaned surface of a diamond remains as a high domed globule whereas in stimulants it spreads faster.

MISSCELANEOUS TEST

Diamond Anatomy• A diamond is comprised of five main

components:

Table

Crown

Girdle

Pavilion

Culet

• One of the most defining characteristics of a diamond is its cut.

• An expertly cut diamond will achieve high levels of brilliance, sparkle, and durability.

• Even if a diamond is graded well in other areas, a poor cut can result in a dull, muted effect.

Diamond Cutting

Diamond Cutting A particular proportion of cutting is essential to bring about brilliance

in a stone. It is emphasized into two aspects

Ratio of proportion of crown and pavilion Angle of cut on crown and pavilion facets w.r.t girdle

Depending on critical angle a stone is cut at a particular angle to obtain total internal reflection so that light refracted into a stone is completely thrown back like a mirror, this aspect is illustrated taking diamond as an example provided below:

Genesis of Diamond Diamonds form about 100

miles below the Earth's surface.

In order for a diamond to be created, carbon must be placed under at least 435,113 pounds per square inch of pressure at a temperature of at least 752 degrees Fahrenheit (400 Celsius).

If conditions drop below either of these two points, graphite will be created.

Genesis of Diamond

Four processes are thought to be responsible for virtually all of the natural diamonds that have been found at or near Earth's surface. One of these processes accounts for nearly 100% of all diamonds that have ever been mined. The remaining three are insignificant sources of commercial diamonds.

1) Deep Source Eruptions

Most commercial diamond deposits are thought to have formed when a deep-source volcanic eruption delivered diamonds to the surface. In these eruptions magma travels rapidly from deep within the mantle, often passing through a diamond stability zone on its route to the surface. Pieces of rock from the diamond stability zone may be torn free and carried rapidly upwards to the surface. These pieces of rock are known as "xenoliths" and may contain diamonds.

Continue….

Most diamonds that we see today were formed millions of years ago. Powerful magma eruptions brought the diamonds to the surface, creating kimberlite pipes (named after Kimberly, South Africa).

2) Subduction Zone Diamonds

Diamonds have been found in rocks that are thought to have been subducted and then returned to the surface. These types of rocks are very rare and no known commercial diamond deposits have been developed within them. The diamonds found in these types of deposits have been very small and not suitable for commercial use.

3) Asteroid Impact Diamonds

Diamonds have been found in and around the craters of asteroid impact sites. These asteroids hit with such force that pressures and temperatures high enough to form diamonds are produced. If the target rock contains carbon the conditions needed to form diamonds might occur within the impact area. These types of diamonds are rare and do not play an important role in commercial diamond mining.

4) Diamonds Formed in Space

• Diamonds have been discovered in some meteorites. These diamonds are thought to have formed in space in response to asteroid impacts.

Diamond in India

Panna Mine, Madhya Pradesh

World occurrence of Diamond Diamonds are mostly found in Africa, India, Russia (Siberia),

South America, Australia, China, and Canada. A good sign that diamonds are in the area is where kimberlite rock is found.

CONCLUSION Compared to most other gem- minerals, the

percentage of gem quality crystals is quite high in diamond.

Kimberlite, lamproite and eclogate are the major sources of diamond.

About 20% of diamonds recovered is of gem quality. The other 80% is been used as industrial diamonds.

Its high hardness, fire ,adamantine lustre, brilliance have made Diamond most valuable gem mineral.

So if our country have more diamond deposits, we can make our country more prosperous.

R.V. Karanth (2000), Gems and Gem Industry In India, GSI, Pp 165-197 Cornelis(2002) Klein & Barbara Dutrow, Mineral Science(after James D.

Dana), John Wiley & Son INC, Pp 557-558. T.M. Babu (1998),, Diamonds in India, GSI, Pp 45,92-94.

www.authorstream.com/Presentation/Ariane-26975-Diamond-Diamondat-glance-HISTORY-DIAMONDS-Early-Middle-Ages-Recent-Times-as-Entertainment-ppt-powerpoint/

www.minerals.net/gemstone/diamond_gemstone.aspx http://geology.com/minerals/diamond.shtml

References

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