1. Flat Edge
The very earliest 12″ microgroove Blue Note LPs (1956/7) were pressed without the slightly raised profile to the edge of the central label area – called a “groove guard” – which is found on all later pressings. The first pressings of BNLP 1500-1557 all have a flat profile, and none after.
The flat edge also refers to the outer rim of the vinyl, where the straight cut edge is later followed by a rounded “beaded rim”
2. Serrated Edge
Another “anomaly” found on a small number of Blue Note re-issues in the Liberty Years (1966-70) is the serrated edge, which was characteristic “trademark” of one pressing plant, identity not known to me.
The significance of serrated edge is close to zero, however it is not “negative”. This pressing was pressed from an original Van Gelder Stereo master. I have perhaps two serrated edge Blue Notes in around fifty Liberty reissues. Uncommon, but not rare.