The highest contrast ratio of the S27C570 is 1000:1. That's 100% less contrast ratio than the most common dynamic contrast ratio of 20000000:1. Medium monitors that have been available for around the same time as the S27C570 dynamic contrast ratios range from Mega Contrast to 100000000:1.
There are a number of alternative PC screens that have a 1000:1 dynamic contrast ratio currently available that you might also want to look at including because of it's better review score, the Samsung LS24C570.
If you are looking for a flatpanel monitor with a higher contrast ratio then you might also want to consider the C24A650X (3000:1 and higher rated), or the S24C750 (£205.26) (3000:1 and higher rated) both from Samsung or the HP Compaq LA2405 (£165.99) (3000:1 and higher rated).