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Method for changing colour of colour-variable natural diamond and diamond obtained thereby

A diamond and natural technology, applied in the field of manufacturing gem-quality diamonds, can solve the problems of uneconomical and unreachable, and achieve the effect of increasing production and reducing cracking and damage

Inactive Publication Date: 2005-12-21
BELLATAIRE INT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Such high pressures are either currently unattainable or uneconomical

Method used

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  • Method for changing colour of colour-variable natural diamond and diamond obtained thereby
  • Method for changing colour of colour-variable natural diamond and diamond obtained thereby
  • Method for changing colour of colour-variable natural diamond and diamond obtained thereby

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0059] In this example, annealing of natural diamonds was performed using a belt device under high temperature and pressure conditions. The belt unit is capable of very high pressures (~60 kbar) and temperatures (~2600°C). Diamonds annealed in accordance with the present invention are described in the following examples using the reaction chamber of the configuration and operating conditions described below.

[0060] figure 2 The reaction chamber assembly is shown schematically. Pre-diced diamond crystals 51 are placed into cylindrical pellets made of high purity graphite or sodium chloride powder. The diamond crystal 51 has been pre-blocked using laser removal of material. Graphite is the recommended material because it does not melt during high temperature annealing. The dimensions of pellet 52 are as follows: 0.76 inches (19.3 mm) in diameter and 0.86 inches (21.8 mm) in height. The pellets 52 are formed by pressing graphite powder and diamond crystals 51 into a hydrau...

Embodiment I

[0064] A pre-blocked 3.49-carat grade IIa brown natural rough diamond was embedded in a graphite pellet pressed from high-purity graphite powder. The diamond was annealed at a pressure of ~60 kbar and a temperature of 2450°C for a holding time of for 6 minutes. The diamond crystal was recovered and visual inspection revealed that its color had changed to clear or colorless.

Embodiment II

[0066]A pre-blocked 3.29 ct class IIa polished brown natural diamond was embedded in a pellet compressed from high-purity sodium chloride powder, and the diamond was annealed at ~60 kbar pressure and 2500°C , hold time is 6 minutes. Visual inspection of the recovered diamond revealed that its color had changed to clear or colorless.

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PUM

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Abstract

The present invention is directed to a method for treating discolored natural diamond, especially Type IIa diamond and Type IaA / B diamond with nitrogen as predominantly B centers, for improving its color. The method includes preblocking and preshaping a discolored natural diamond to prevent its breakage in a high pressure / high temperature (HP / HT) press, placing said discolored natural diamond in a pressure transmitting medium which is consolidated into a pill. Next, the pill is placed into a HP / HT press at elevated pressure and elevated temperature within the graphite-stable or diamond-stable range of the carbon phase diagram for a time sufficient to improve the color of said diamond. Finally, the diamond is recovered from said press. Colorless and fancy colored diamonds can be made by this method.

Description

technical field [0001] The present invention relates generally to the manufacture of gem quality diamonds (colorless and colored), and more particularly to the manufacture of gem quality diamonds from low grade discolored diamonds or from so called "brown" diamonds. Background technique [0002] Diamonds are generally divided into four main grades, which are denoted by Grade Ia, Ib, IIa, IIb, and in practice there is a smooth variation in the concentration / distribution of impurities between the above four grades, therefore, there are There are intermediate varieties between them. The main impurity in Grade I diamonds is nitrogen. Diamonds of this grade can be divided into Ia diamonds and Ib diamonds. In Ia diamonds, nitrogen is in the state of paired aggregation of four nitrogen atoms (IaA grade) or agglomeration (IaB) or a mixture (IaA / B) ) and in grade Ib diamonds, nitrogen exists only as isolated single nitrogen atoms. Some diamonds also contain three groups of nitroge...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01J3/06B24B1/00B24B19/16B30B11/00C01B31/06
CPCB01J3/062B01J3/067B01J2203/062B01J2203/0655B01J2203/0695B24B19/16B30B11/004B30B11/007B01J3/06
Inventor T·R·安东尼W·F·班霍尔策J·K卡西Y·卡迪奥格卢A·C·史密斯W·E·杰克逊S·S·瓦加拉尔S·W·维布
Owner BELLATAIRE INT
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