A method and apparatus for measuring a parameter of an object is disclosed. The object is placed within a vessel configured to contain the object via an opening in the vessel. A cover is placed over the opening. A securing device is used to secure the cover to the vessel. A measurement device is used to measure the parameter of the object at a raised pressure. The parameter can be a nuclear magnetic resonance parameter of the object. A fluid in the vessel can be heated to raise the pressure within the sealed vessel. In various embodiments, the securing device can be a second cover or a clamp, for example. The measured parameter can be used in determining a suitability of the object for use in downhole environments.