The inscription of a Fibre Bragg Grating (FBG) in optical fibres allows them to be used as sensors, being capable of decoding small variations of strain; temperature; pressure; loading; bending; or even refractive index, by means of a shift in the reflected wavelength. Nevertheless, broadening their sensitivity and operation range would be desirable. This may be achieved by appropriated fibre coating. Diamond possesses a set of extreme properties, such as high thermal conductivity, hardness and resistance to hazard environments. Furthermore, it is known for its excellent biocompatible response, so it may be suitable to be used as a coating material for biological sensors. In this paper, the results of the optimization process of diamond coatings on optical fibre sensors is presented, considering their potential use for practical biological purposes.