

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.

