You are living in a OP world were a magazine revealed Shanks had the highest bounty among the old Emperors Just for the manga to do the complete opposite. Same, the VCs somethimes have new information and sometimes they are just like us or worse (Zoro and Yamato CoC).
Don't even get me started with the anime.
I have no faith at all in those sources and I think they'll Just use the anime coloring because It's easier, even if doesn't make sense: hamon aside, the sword can be black, blue, green or every other damn color you can draw using "black" in a black and white manga...but one can't be: white, because every damn white sword of this manga was drawn, surprise surprise, white lol, because It's white.
Obv they went for white.
And since the official volume long came out, and Oda didn't change anything, It's clear he really wanted to use black for Ryo's sword.
For me only two sources matters:
- the manga (let's see if the next time it'll look Just like a BB again, but as I said Oda didn't change the scene in the official volume);
- a volume cover, where Ryokugyu Is bound to be drawn sooner or later.