One way is by the measurements of the stone. I've had three or four Barber's Delight Eschers come, and go. All of the BD I've ever seen are the same size, IIRC that is 2"x6" for the main stone, + the slurry stone, as opposed to different sizes for other Eschers. The most common being the 7x1&5/8". The shorter boxed stones are many times
5x2&1/2 +slurry. Here is an old thread with some pix of various
http://straightrazorpalace.com/hones...tml#post611426