EOSC FINAL EXAM - UNIT B LATEST UPDATE
Summarize the historical sources of diamond prior to 1867 - ANSWER Alluvial
(panning) deposits in India
Discuss the significance of the discovery of diamonds in South Africa in 1867 -
ANSWER Discovery of primary source rock (kimberlite) instead of just secondary
(alluvial) deposits -> new demand for diamonds developed so it was not just for royalty
and uber wealthy anymore
Summarize how the dominance of the De Beers group has changed in the last century -
ANSWER De Beers controlled South African mining, then other mines came around
Russian Mir Mine*, Aussie Argyle Mine, Diavik and Ekali mines in Canada. Now De
Beers only has 7 major mines of 20 worldwide
Use the diagnostic properties of diamond (such as thermal conductivity, composition,
crystal structure, primary morphology, etc.) to identify it. - ANSWER Very high thermal
conductivity, octahedral crystal habit, very hard (hardest material on earth), fluorescent
Describe the cleavage of diamond and its importance for diamond cutters - ANSWER 4-
directional perfect cleavage so it's great for diamond cutters
Differentiate between Type Ia, Ib, IIa, IIb diamonds in terms of composition and colour -
ANSWER Ia - aggregated N impurities (98% of diamonds). Yellow hue due to blue light
absorption
Ib - isolated single N impurities
IIa - flawless. no N or B impurities. (2% of diamonds). Clear white color
, IIb - B impurities - blue/grey hue as all other colours except blue are absorbed.
Extremely rare.
Identify the cause(s) of different colours of diamond - ANSWER D - flawless, no
impurities
Blue/grey - boron impurities
Yellow - N impurities
Pink/Purple/Red - Deformed crystal structure
Green - natural irradiation (Dresden Green)
Black - graphite inclusions
Identify common diamond treatments and methods of creating synthetic diamonds -
ANSWER Colour treatments - irradiation and temp/pressure annealing
Clarity treatment - laser drilling, acid boiling, glass filling
Synthetics - CVD ("3D printer") and high pressure high temp
Describe the geological conditions necessary for diamond formation and how diamonds
are brought from the mantle to the surface - ANSWER Formed min. 140km below the
Earth's surface. But it is typically too hot (1500*C) so need a cool pocket of 950*-1400*
to form at the right depth, so it is enough pressure but cool enough. Otherwise they will
be melted.
Brought to surface by magma coming up the carrot-shaped kimberlite pipe, erupting in a
specific type of volcano. As it shoots up the pipe, the magma picks up the diamonds
and deposits them at the surface.
Explain why diamonds are rare - ANSWER Formed deep below the Earth's surface and
very specific geological conditions required to bring them up to the surface
Describe the global distribution of diamond deposits, geographically and geologically -
ANSWER Kimberlite pipes only found in old/cold archaen-age cratonic basement rocks.
Canadian Shield, Siberia, Africa, Greenland, etc.
Briefly summarize the change in diamond production by country through history -
ANSWER 1870 - 1930: primarily South Africa
1930-1960: other African nations
1960: Russia becomes dominant
1980: Australia
1990: Canada
Today: Australia, Botswana, Canada top 3
Define and describe the 4(+1) C's and how each affects the value of a diamond -
ANSWER Colour - DEF considered colourless/ J-Z is yellow
Cut - Ideal/Shallow/Deep (enhance brilliance)
Clarity - IF, VVS, VS, SI, I
Carat - larger size increases price exponentially
5th C - country of origin ( ethical)
Summarize the historical sources of diamond prior to 1867 - ANSWER Alluvial
(panning) deposits in India
Discuss the significance of the discovery of diamonds in South Africa in 1867 -
ANSWER Discovery of primary source rock (kimberlite) instead of just secondary
(alluvial) deposits -> new demand for diamonds developed so it was not just for royalty
and uber wealthy anymore
Summarize how the dominance of the De Beers group has changed in the last century -
ANSWER De Beers controlled South African mining, then other mines came around
Russian Mir Mine*, Aussie Argyle Mine, Diavik and Ekali mines in Canada. Now De
Beers only has 7 major mines of 20 worldwide
Use the diagnostic properties of diamond (such as thermal conductivity, composition,
crystal structure, primary morphology, etc.) to identify it. - ANSWER Very high thermal
conductivity, octahedral crystal habit, very hard (hardest material on earth), fluorescent
Describe the cleavage of diamond and its importance for diamond cutters - ANSWER 4-
directional perfect cleavage so it's great for diamond cutters
Differentiate between Type Ia, Ib, IIa, IIb diamonds in terms of composition and colour -
ANSWER Ia - aggregated N impurities (98% of diamonds). Yellow hue due to blue light
absorption
Ib - isolated single N impurities
IIa - flawless. no N or B impurities. (2% of diamonds). Clear white color
, IIb - B impurities - blue/grey hue as all other colours except blue are absorbed.
Extremely rare.
Identify the cause(s) of different colours of diamond - ANSWER D - flawless, no
impurities
Blue/grey - boron impurities
Yellow - N impurities
Pink/Purple/Red - Deformed crystal structure
Green - natural irradiation (Dresden Green)
Black - graphite inclusions
Identify common diamond treatments and methods of creating synthetic diamonds -
ANSWER Colour treatments - irradiation and temp/pressure annealing
Clarity treatment - laser drilling, acid boiling, glass filling
Synthetics - CVD ("3D printer") and high pressure high temp
Describe the geological conditions necessary for diamond formation and how diamonds
are brought from the mantle to the surface - ANSWER Formed min. 140km below the
Earth's surface. But it is typically too hot (1500*C) so need a cool pocket of 950*-1400*
to form at the right depth, so it is enough pressure but cool enough. Otherwise they will
be melted.
Brought to surface by magma coming up the carrot-shaped kimberlite pipe, erupting in a
specific type of volcano. As it shoots up the pipe, the magma picks up the diamonds
and deposits them at the surface.
Explain why diamonds are rare - ANSWER Formed deep below the Earth's surface and
very specific geological conditions required to bring them up to the surface
Describe the global distribution of diamond deposits, geographically and geologically -
ANSWER Kimberlite pipes only found in old/cold archaen-age cratonic basement rocks.
Canadian Shield, Siberia, Africa, Greenland, etc.
Briefly summarize the change in diamond production by country through history -
ANSWER 1870 - 1930: primarily South Africa
1930-1960: other African nations
1960: Russia becomes dominant
1980: Australia
1990: Canada
Today: Australia, Botswana, Canada top 3
Define and describe the 4(+1) C's and how each affects the value of a diamond -
ANSWER Colour - DEF considered colourless/ J-Z is yellow
Cut - Ideal/Shallow/Deep (enhance brilliance)
Clarity - IF, VVS, VS, SI, I
Carat - larger size increases price exponentially
5th C - country of origin ( ethical)
