Fine grained jade are susceptible to having cotton/snow features too, one way to tell is if you see multiple white spots that looks like a small ball of cotton like those from Q-tips in a way

Also if I read that correctly, yes coarser grains (or as I like to call it, sugary grained) will have the sparkly effect like Fly’s Wing, if not then I’m going to guess the one Nandar showed was a jadeite bangle that has metal intrusion in the bangle which causes (and has happened) the sparkle effect. Fine grained jade are also susceptible to it to a certain extent but are invisible unless your shine a light directly at it.
Also your collection of bangles are lovely! Although I am worried about your purchase from Maithong as people have had unsavory experiences from her to where some had to file a claim in the ecommerce website she was selling in for a refund cause she refuses even when they had proof of it being treated.
Edit: Grade C jade is not much better than Grade B since it’s still treated, just that dye is injected into it’s porous structure and who knows what ingredients are in the dye chemicals. I certainly wouldn’t be happy wearing it if someone told me it’s Grade A when it’s Grade C

Luckily Chelsea Filter and UV light should be enough to detect dyeing.