Firstly, watch your language for one. Reported anyway.
Second of all.
Luffy used what appears to be Black Haki after the Time-Skip in front of the entire crew.
Yet, Franky only realises that Luffy is a haki user at Punk Hazard because he made contact with a Logia.
If Haki was visibly Black, Franky wouldn't be asking if Luffy is using Haki, he'd know already because Luffy used Haki against the Kraken on the way to Fishman Island which assuming you're not aware is before Punk Hazard arc.
More so.
Chapter 504
Chapter 947: Same Scene
If you've not noticed the difference:
- Rayleigh's hands are not Black pre-skip chapter 504.
- Rayleigh's hands are black post-skip 947.
Rayleigh was always using Haki; it's only Black now because Luffy can recognise Haki and Oda shades Haki as Black so we know it's the stronger form of Armament being used.
Haki is referred to as being invisible, not Black.
Something else you probably are clueless about is this:
When Mihawk said any Blade can become like a Black blade, it's not necessarily referring to being literally black. Being Hard is just the property of Black blades. Haki makes things hard, thus any blade can become "like" a black blade and not get broken or nicked.