Contrast ratios are a fools game. It pushed by plasma guys. First, there are TWO types of contrast numbers, INTRINSIC and EXTRINSIC. In a black room, you measure white (say, 500 nits) and then you measure black (say, .5 nits). .5 divided into 500 is 1000. This means 1000:1, which really is not bad. This is the INTRINSIC contrast ratio.
Now, take this displays into a lit room. NOW, white is still 500 nits but black can be as high as 100+ nits because 4% of the ambient light will bounce off the front, diluting black and make for a contrast ratio of 5:1. This is the EXTRINSIC ratio. AND IT IS ON THE SAME DISPLAY.
Here is the joke... Plasma got challenged by LCDs a few years ago. In order to look good on paper, plasma started to advertise 10,000:1 and greater. Now think about it. Plasma emit lit. Black on a plasma emits ZERO lit. SO, in a darkroom, how many ZERO NITS goes into 500 nits? 10,000, 20,000.... why not a MILLION :1. Now, take the plasma outside into the light. Now black can reflect about 200 nits (yes, they are very reflective if there is something to relfect. Their black in the light is much worse than LCDs. Plasma's extrinsic ratio is probably 3:1 in the worse case.
Watch out for cetain specs. It does not necessarily mean anything.