I'm the proud owner of 2 Vintage Norton blacks that show translucency about .5 inches deep. Is this common with old Norton blacks?
I've got a green label that's identical to my dans black arks.Depends on the era.
In my experience if you got back past a certain point pretty much anything black that Norton sold was also translucent. Sample size of maybe 10-15 stones though, so take that for what it's worth.