Cetane is less of a factor than lubricity. Canadian diesel must meet a maximum 460Ám wear scar rating. US diesel only has to meet a 520Ám maximum wear scar rating. I believe European diesel specifications allow only a maximum of 350Ám wear scar.
Smaller wear scar is better, meaning that on a test rig, the fuel with greater lubricity will result in a smaller scarring on the test surface.
2016 GLE 350d - White on Black