Hi James,
ckng515 is correct. The JV strap is nubuck alligator strap. The interesting thing is nubuck is normally associated to calf or cowhide. Nubuck is the process where the hide is buffed on the outside or top grain. The end result is similar to suede, a fine soft velvety finish. It is important to note that in suede, the hide is buffed on the inside or the flesh side.
With regards to the assolutamente, the hide is calf but it is untreated (or minimal treatment) and retains the natural finish.
Hope that helps.