In many fruits, and melons in particular, it is desired to replace destructive firmness measurement methods, by non-destructive ones. A new non-destructive method for evaluating melon firmness and shelf-life is presented by a study on two melon samples of the Galia cultivar, one with sparsely netted skin and the other with relatively densely netted skin. The line taken assesses the performance of the non-destructive fruit firmness sensor, which is based on vibrational excitation, versus the conventional destructive test which measures the applied piercing force on the inspected fruit by a penetrometer. The distribution of the differences between the readings of the two methods, after suitable translation of the non-destructive readings to the piercing force scale in Newtons, shows about 12-15% difference of full scale, in about 70% of the population. A comparison is also made to sensory hand squeezing judgments of expert inspectors. An independent measure for assessing the sensitivity of the non-destructive sensor to melon aging, is presented by taking time spaced firmness readings on a fruit sample, at the same locations of each fruit. The superior sensitivity of the non-destructive method to melon ageing, renders it particularly suitable for sorting melons by predicted shelf-life. Freshly harvested melons, that show higher readings will generally have a longer shelf-life.