The contrast ratio describes the range of brightness levels a set can display. Better contrast ratios display more subtle shadows and hues, and thus better detail. However, the way manufacturers measure such ratios varies widely. Indeed, the specification has been so thoroughly discredited that if a salesperson uses it as a selling point, you should shop somewhere else.
We use the same method for examining contrast ratios in all the TVs we test, so we can say roughly how well they compare to each other. Nevertheless, it’s still best to see for yourself how a TV displays shadow detail by finding a movie with dark scenes and seeing how well it reveals detail in the shadows of, say, a Harry Potter movie. Experiment with the TV’s brightness, sharpness and other picture settings before making a final judgment. (Hint: select “movie” or “cinema” mode on the TV.)
Bottom line: You can ignore manufacturers’ contrast-ratio specs, since they are not comparable across brands.