Jeweller - November 2021

S
CHART A: DIAMOND
ORIGIN RATIO
Approximately 99 per cent
of the world's diamonds are
lithospheric, while less than
1 per cent are super-deep
and 0.1 per cent are oceanic.
Lithospheric – 99%
Super-Deep – 0.90%
Su
Oceanic – 0.10%
Oceanic – 0.10%
Super-Deep – 0.90%
Lithospheric – 99%
GLOSSARY OF TERMS
DEFINING DIAMONDS
SCIENTIFIC REPORT
Super-Deep Diamonds
Scientific terminology in diamond formation
CARBON CYCLE – The shifting of the element carbon
between different ‘reservoirs’ on Earth – rocks, soil, ocean,
and atmosphere, plants – through chemical reactions and
tectonic activity
KIMBERLITIC ERUPTION – Catastrophic explosions
in the Earth's mantle which transport super-deep and
lithospheric diamonds to the surface
LITHOSPHERIC DIAMONDS – Diamonds that form in the
continental lithosphere – the outermost, rigid layer of Earth
– between 150–300km from the surface, from ambient
carbon; they are by far the most abundant diamonds
MANTLE PLUME – The ballooning heated rocks in the
mantle that create kimberlitic eruptions
METALLIC MELT – Pockets of molten metallic liquid –
comprised of iron and nickel, among other elements – that
occur deep in the Earth’s mantle, in which large, Cullinanlike
diamonds form
OCEANIC DIAMONDS – Diamonds that form as a result of
plate tectonics, subducting the ocean floor and its carbon
and other minerals into the mantle
SUBDUCTION – The process whereby Earth’s tectonic
plates collide and sink back into the mantle underneath
another plate
SUPER-DEEP DIAMONDS – Diamonds that form
very deep in the Earth’s mantle, around 400km below
the surface; less than 1 per cent of diamonds are superdeep
diamonds
TRANSITION ZONE – The area deep within Earth’s
mantle in which pressure and temperature conditions allow
the formation of metallic melt, from which the super-deep
diamonds form