The iPhone X OLED display is a diamond matrix PenTile arrangement, as opposed to the traditional RGB stripe arrangement.

From Rene Ritchie’s iPhone X review:

To begin with, Apple has sourced its OLED panels from Samsung Display, which offers the best and most mature phone solution currently on the market. (Pixel 2 XL was sourced from LG Display.)

That does mean the iPhone X is stuck with a diamond pixel arrangement, which has oval green pixels with square red and blue pixels arranged around them, rather than the RGB stripe traditionally used for LCD displays. It’s a way to mitigate against the significantly lower lifespan of blue pixels in OLED, and it’s what can currently be supplied at scale.

Read the rest of Rene’s review for more detail, but bottom line, you end up with more green than red and blue.

There have been a number of pictures showing the overall look of this arrangement (including the images in Rene’s review), but I found this tweet from Steve Troughton-Smith‏ really brought a sense of what the diamond matrix arrangement meant in real life:

So what does PenTile mean in practice on iPhone X? Only green is 'true 3X' You need exceedingly tiny text to notice the effect, just about the limits of decent human vision. (full-res test PNG: https://t.co/iuR0SQzXoz) pic.twitter.com/XFr2cawtV0

— Steve Troughton-Smith (@stroughtonsmith) November 11, 2017

Tap the image and notice how much sharper the green text is than the red or blue text on either side.

With that image in mind, go back to Rene’s review and read what he has to say about the iPhone X display and how Apple gets the most out of it. Great stuff.