A measuring sensor includes an elongated shell part, manufactured from a synthetic gemstone material or ceramic material, is provided with a first end and a second end, the first end being arranged in a process medium to be measured. A housing structure is manufactured from a material softer than the synthetic gemstone material or the ceramic material and arranged to surround the measuring electronics. The second end of the elongated shell part is arranged to be supported against the housing structure. The elongated shell part is fastened to the housing structure by a connecting piece manufactured from a material having a hardness property between hardness properties of the material of manufacture of the elongated shell part and the material of manufacture of the housing structure.