Possibility of Natural Diamond Synthesis under Conditions of Cavitation, occurring in a Fast-moving Magmatic Melt

E. M. GALIMOV

doi:10.1038/243389a0

RECENT DEVELOPMENT IN DIAMOND SYNTHESIS

International Journal of Modern Physics B ◽

10.1142/s0217979208038685 ◽

2008 ◽

Vol 22 (04) ◽

pp. 309-326 ◽

Cited By ~ 3

Author(s):

CHANGLE CHEN ◽

QIANWANG CHEN

Keyword(s):

Carbon Dioxide ◽

Natural Diamond ◽

Chemical Vapor ◽

Diamond Synthesis ◽

Diamond Crystals ◽

High Pressure High Temperature ◽

Recent Developments ◽

Reducing Environment ◽

Important Progress ◽

Large Diamond

The high pressure-high temperature (HPHT) method led to wide applications of artificial diamonds in industry. Low temperature coating of diamonds has been studied for some time, and chemical vapor deposition has been developed. In this contribution, we will focus on the most recent developments in diamond synthesis, and especially the important progress upon hydrothermal synthesis and the reduction of carbide (HSRC), which has attracted more and more attention due to its great commercial potential. Especially, we will discuss the synthesis of colorless, large diamond crystals from the reduction of carbon dioxide or carbonates. In addition, some recent progress on the theoretical studies of the metastable nucleation and growth of diamonds will also be reviewed. Finally, theories about the genesis of natural diamond were briefly reviewed, and a new theory based on our experimental results was proposed, which suggests that diamond within the Earth could be produced from carbon dioxide wherever carbon dioxide existed and the conditions (e.g., temperature, pressure, and reducing environment) are satisfied.

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The value of Electron Microscope studies of imperfect natural diamonds

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174102 ◽

1990 ◽

Vol 48 (4) ◽

pp. 194-195

Author(s):

J C Walmsley ◽

A R Lang

Keyword(s):

Electron Microscope ◽

Classification Scheme ◽

Natural Diamond ◽

Sudden Change ◽

Growth Conditions ◽

Diamond Growth ◽

Major Constituent ◽

Natural Diamonds ◽

Type Ia ◽

Platelet Defects

Interest in the defects and impurities in natural diamond, which are found in even the most perfect stone, is driven by the fact that diamond growth occurs at a depth of over 120Km. They display characteristics associated with their origin and their journey through the mantle to the surface of the Earth. An optical classification scheme for diamond exists based largely on the presence and segregation of nitrogen. For example type Ia, which includes 98% of all natural diamonds, contain nitrogen aggregated into small non-paramagnetic clusters and usually contain sub-micrometre platelet defects on {100} planes. Numerous transmission electron microscope (TEM) studies of these platelets and associated features have been made e.g. . Some diamonds, however, contain imperfections and impurities that place them outside this main classification scheme. Two such types are described.First, coated-diamonds which possess gem quality cores enclosed by a rind that is rich in submicrometre sized mineral inclusions. The transition from core to coat is quite sharp indicating a sudden change in growth conditions, Figure 1. As part of a TEM study of the inclusions apatite has been identified as a major constituent of the impurity present in many inclusion cavities, Figure 2.

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