摘要：

A diamond element () having a convex surface is disclosed, the convex surface including a spherical segment for which the maximum peak to valley deviation from a perfect spherical surface is less than about 5 μm. The diamond element () may be a solid polycrystalline diamond material and/or may comprise base material which is coated with diamond. Alternatively or in addition, the RMS deviation from a perfect spherical surface may be less than about 500 nm, or the RMS roughness less than about 30 nm. A diamond element () with a radius of curvature less than about 20 mm is also disclosed. In one aspect a diamond element () having a conical half-angle greater than about 10° is described. Diamond elements () of this type are intended for use as metrology tips. Key to this invention is the realization that a diamond surface, particularly a diamond surface with low Ra (roughness) and which is free of defects such as pits, digs and scratches, accumulates less material from the surface being measured, and thus provides a longer life.

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