Watch the Keith Richards online guitar lesson by Jeff McErlain from Kings of Tone
Open G from low to high is D, G, D, G, B, D. Keith actually has many of his guitars strung without the low E string because he said "It gets in the way". Really take a look at some of the main voicings in this lesson, you will see them over and over again in many Stones tunes. In many bands like the Stones one guitarist may be in standard tuning and the other in an open tuning. This is often the case with the Black Crowes, a very Stones influenced band.