I know it's never good to
assume anything, but for the most part unless a seller/dealer specifically says that their
juice is
VG then it probably is
PG.
I just looked at the label on my last 50ml bottle of 24mg Marlb from Rocky Mountain Vapor and it does not say whether it is PG or VG, but as thin as is from the bottle, I am about 99% sure that it is PG.
You could always email them and get a definate answer.