Anglo American has been granted a patent for a blue colored single crystal CVD synthetic diamond material. The material consists of multiple layers with different defect compositions and colors, resulting in a uniform color when fabricated into a round brilliant cut diamond. The layers include boron dopant and single substitutional nitrogen dopant, with specific concentration and thickness requirements. The patent also introduces a figure of merit for visibility of individual layers. GlobalData’s report on Anglo American gives a 360-degree view of the company including its patenting strategy. Buy the report here.
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Patent granted for blue coloured synthetic diamond with uniform color
A recently granted patent (Publication Number: US11746436B2) describes a blue colored single crystal CVD synthetic diamond material. The material consists of multiple layers, with at least two sets of layers that differ in terms of their defect composition and color. The defect type, defect concentration, and layer thickness of each set of layers are carefully controlled to ensure that if the material is fabricated into a round brilliant cut diamond with a table to culet depth greater than 1 mm, it will have a uniform blue color as viewed by the naked human eye under standard ambient viewing conditions.
The first set of layers in the diamond material contains boron dopant at a concentration sufficient to produce a blue coloration, while the second set of layers has a lower concentration of boron dopant and includes single substitutional nitrogen dopant. The first set of layers has an uncompensated boron dopant concentration between 0.05 ppm and 5.00 ppm, while the second set of layers has a single substitutional nitrogen dopant concentration between 0.1 ppm and 5 ppm. The second set of layers also has a greater layer thickness than the first set, with a minimum thickness of 0.1 mm.
The patent also introduces a figure of merit (FM) for the visibility of individual layers, which should not exceed 0.15. This figure of merit is calculated based on the layer thickness, solid boron concentration, and round cut brilliant depth. The patent claims that the blue colored diamond material can have at least 5, 10, 20, 30, 40, or 50 layers.
The patent also includes claims related to the fabrication method of the blue colored diamond material. The method involves varying the dopant gas concentration in a single crystal CVD synthetic diamond growth process to form the material with multiple layers. The dopant gas concentration and the time period of variation are controlled to ensure a uniform blue color in the resulting diamond when viewed in different directions. The method may also include annealing the diamond material.
Overall, this patent describes a blue colored single crystal CVD synthetic diamond material with controlled defect composition and layer thickness, resulting in a uniform blue color when fabricated into a round brilliant cut diamond. The patent also outlines a method for producing this material through a carefully controlled growth process.