The S23C450 has a maximum contrast ratio of 1000:1. That's 100% less contrast ratio than the most frequently found dynamic contrast ratio of 20000000:1. Across all medium monitors that have been on the market for more than two years the contrast ratio ranges from Mega Contrast to 100000000:1.
Other LCD screens that have a 1000:1 dynamic contrast ratio currently available that you might want to look at include because of it's better review score, the 23M45 ($249.97), or the 24M45 both from LG or the Samsung LS23C350.
If the contrast ratio of this PC monitor is not high enough for you then you might also want to look at the Samsung C24A650X (3000:1 and higher rated), the iiyama X2485WS (3000:1 and higher rated), or the Benq BL2410 (3000:1 and higher rated).