Recently we have customers are confused with the iPhone screen display color.
Here is the truth and reason of the display color difference

The display color of the lcd screen is mostly determined by the mother board IC,different brand IC, different display color,because APPLE company use 3 suppliers , TSMC(Taiwan Semiconductor Manufacturing Company Limited) , Samsung, and Korea Hynix for the mother board IC, these 3 different IC companies make the screen show different color, so you can see even same iPhone models may have different display color, different iPhone models the display colors are also different.

And Apple use 3 suppliers Sharp, JDI(Japan Display Inc.) and LG for iPhone lcd screens, the screens produces by these 3 lcd companies are also different, Sharp screen has cold color( a little blue), JDI screen is warm color, LG screen has both warm and cold color. So the original APPLE official screens have both warm and cold clolor, but based on the research data, mostly are warm color.

However, for your clients who come to your shop to repair, they have been use their phone for long time, so they are used to the display color of their own screens, if they said the color is different you can explain to them as above and show them the picture.
So where is IC chip on the screen?
Below is the picture of the IC chip location, it is hidden under the shield for protection.

We removed the shield to show the exact location.

Yes, that small chip makes that much difference.
Thank you ETtrends for great research.