Custom color gradient for ArcGIS ESRI map

The current ESRI map offers 8 preset color gradients to display values from lowest to highest.

I often need to map positive (green) and negative (red) values on a map, where zero values are white. For example growth rates, profit/loss etc.
For this I would need to customize the color with a diverging gradient, where the midpoint color (white) can be set to 0.

Note that this is already available in the "standard" Bing map, please also enable it in ESRI to make it much more powerful!