I think the Norton marketing department decided to follow Shapton, that always rated their 8K finer than 3 micron... This only confirms that these firms can actully say what they want in advertising. The value of truth is reversely correlated to the bank accounts of the stockholders.
Bart.
Marketing is always a hazy truth but its the results that count.
I won't set or restore bevels on any eBay junker with anything finer than 1k.