Can you visually tell apart a pewter and a black pewter?

[Royal Hijinx]

With regards to the "granite" look of the rings (alien head with one eye) of the black pastel, I looked at the morph guide just now and seems like the BHB line and Graziani line Cinnamons have clear rings, the black pastel has granite looking rings. But the Ralph Davis line of Cinnamons are also like the black pastels in that they have the "noise" in the rings. Gave me a lot better understanding to translate into pewters. However, how do you tell difference between black pastel and Ralph Davis line of Cinnamons? They are mentioned as being very similar with the same noise in the rings.

Then overall color would be up next.