I'm going to say no on this. My glider is a black beauty and has very DARK and PROMINENT chin straps but the do not meet in the middle. His joeys are also Black Beauties but the chin strap does not meet.
Joeys Chin straps:
Also, not EVERY glider with a chin strap is a black beauty. I see people ALL the time saying their glider is a black beauty due to it having chin straps. ANY classic colored glider will have chin straps, to what extent depends on the glider. There are other factors that determine whether the glider in question is a black beauty.
I believe these include:
-dark prominent chin strap that extends WAY under but does not have to meet in the middle.
-the dark black on the knuckles just above the last joint on the hands.
-BLACK ears, not grey or pink-black.
-A thick BLACK stripe that runs down to the gliders nose.
-and a dark undercoat on the belly.
-and black around the muzzle.
However,, I strongly believe that a glider must have ALL of these characteristics to be considered a black beauty.
Pictures of classic greys that by some standards would be considered black beauty:
Notice the dark chin straps on these guys:
I wish I could get pics of my boys chin straps. They definitely do not meet in the middle, but would say he is a black beauty. Same with the joey in the first pic-her chin straps did not meet in the middle.
If I'm way off on this please let me know, but these are the observations I've made, and want to get something out there to help clear things up for people that may not completely understand.