The Asus VG27AH has a maximum contrast ratio of 80000000:1. That's over four times the contrast ratio of the most frequently found dynamic contrast ratio of 20000000:1. The worst contrast ratio of all medium monitors that were launched around the same time as the VG27AH is Mega Contrast and the best is 100000000:1.
It may also be worth also looking at one of the other LCD screens that have an 80000000:1 dynamic contrast ratio currently available including the AOC u3477 (£499.98), or the Philips 272G5DJEB (£199.97) which has a better Rating.
If the contrast ratio of this PC display is not high enough for you then you might also want to look at the Acer CB270HU (£234.97) (100000000:1 and cheaper) or the Asus PB287 (£228.96) (100000000:1 and higher rated).