A fluid property of live crude oil removed from an earth formation is determined using nuclear magnetic resonance (NMR) measurements. A pressure cell, located on or near the earth's surface, and in which the live crude oil is disposed, is provided. An NMR tool capable of making NMR measurements on the live crude oil is provided, as is a database linking existing NMR data and the fluid property. A mapping function is created from a combination of radial basis functions and parameters of the mapping function are derived using the database. NMR data are acquired on the live crude oil using the NMR tool, and the fluid property is estimated from the acquired NMR data using the mapping function.