Abstract: A polycrystalline chemical vapor deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centered on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A polycrystalline chemical vapor deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centered on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 70 mm; a thickness equal to or greater than 1.3 mm; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A free-standing non-planar polycrystalline CVD synthetic diamond component which comprises a nucleation face and a growth face, the nucleation face comprising smaller grains than the growth face, the nucleation face having a surface roughness Ra no more than 50 nm, wherein the free-standing non-planar polycrystalline CVD synthetic diamond component has a longest linear dimension when projected onto a plane of no less than 5 mm and is substantially crack free over at least a central region thereof, wherein the central region is at least 70% of a total area of the free-standing non-planar polycrystalline CVD synthetic diamond component, wherein the central region has no cracks which intersect both external major faces of the free-standing non-planar polycrystalline CVD synthetic diamond component and extend greater than 2 mm in length.

Abstract: A free-standing non-planar polycrystalline CVD synthetic diamond component which comprises a nucleation face and a growth face, the nucleation face comprising smaller grains than the growth face, the nucleation face having a surface roughness Ra no more than 50 nm, wherein the free-standing non-planar polycrystalline CVD synthetic diamond component has a longest linear dimension when projected onto a plane of no less than 5 mm and is substantially crack free over at least a central region thereof, wherein the central region is at least 70% of a total area of the free-standing non-planar polycrystalline CVD synthetic diamond component, wherein the central region has no cracks which intersect both external major faces of the free-standing non-planar polycrystalline CVD synthetic diamond component and extend greater than 2 mm in length.

Abstract: A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 70 mm; a thickness equal to or greater than 1.3 mm; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient ?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: A polycrystalline chemical vapour deposited (CVD) diamond wafer comprising: a largest linear dimension equal to or greater than 125 mm; a thickness equal to or greater than 200 ?m; and one or both of the following characteristics measured at room temperature (nominally 298 K) over at least a central area of the polycrystalline CVD diamond wafer, said central area being circular, centred on a central point of the polycrystalline CVD diamond wafer, and having a diameter of at least 70% of the largest linear dimension of the polycrystalline CVD diamond wafer: an absorption coefficient?0.2 cm?1 at 10.6 ?m; and a dielectric loss coefficient at 145 GHz, of tan ??2×10?4.

Abstract: The invention relates to a speaker dome comprising: a polycrystalline diamond dome body formed of a material of high stiffness with a Young's modulus greater than 50 GPa and having respective inner and outer surfaces; and a coating on at least one side of the dome body, wherein the coating comprises an optically refractive metal compound layer which is semi-transparent and which forms one or more colors via interference of reflected light from front and rear surfaces of the layer. The invention also relates to a diamond component comprising: a diamond body; and a coating on at least one side of the diamond body, wherein the coating comprises at least two layers including a first layer bonded to the at least one side of the diamond body and a second layer disposed over the first layer, the second layer being an optically refractive metal compound coating which is semi-transparent and which forms one or more colors via interference of reflected light from front and rear surfaces of the second layer.

Abstract: The invention relates to a speaker dome comprising: a polycrystalline diamond dome body formed of a material of high stiffness with a Young's modulus greater than 50 GPa and having respective inner and outer surfaces; and a coating on at least one side of the dome body, wherein the coating comprises an optically refractive metal compound layer which is semi-transparent and which forms one or more colours via interference of reflected light from front and rear surfaces of the layer. The invention also relates to a diamond component comprising: a diamond body; and a coating on at least one side of the diamond body; wherein the coating comprises at-least two layers including a first layer bonded to the at least one side of the diamond body and a second layer disposed over the first layer, the second layer being an optically refractive metal compound coating which is semi-transparent and which forms one or more colours via interference of reflected light from front and rear surfaces of the second layer.