Hi Derek
I have a carpet shop near to me that still suopplies and fits sisal, I took a photo of the range he carries - see picture below.
He told me they do everything they can to talk people out of fitting the stuff and that the fitters hate fitting it.
It has a straw / dry grass texture to it, though in the same shop there was a high end wool carpet that looked and felf incredibly similar to the sisal stuff, in which case I guess a burn test would tell them apart.
As you can see it comes in a wide range of colours too, so don't assume it's only available in natural.
Paul