I have two bottles of Woolite Black detergent in my wardrobe, both purchased with good intentions after I came across two great-fitting pairs of inky-black jeans. I bought the first bottle after I found a pair of Madewell jeans in a black so black that they made my legs look almost 2-D, like they were stamped into space. The second bottle came about because I forgot I already owned the first, after I came across a pair of cropped Cheap Mondays that came in a black so black that they made anything around them super-colourful in comparison.
I'm telling you this story, because, obviously, I never used either of those Woolite Blacks and both pairs of jeans are now more heather-grey than black. They're more George Clooney than Dita Von Teese — and, it turns out, I'm sort of digging them this way. Black jeans that aren't so black means you've had to launder them a dozen times or more, which means a dozen cycles' worth of escapades and romps. My black jeans are no longer new nor black and I'm much less precious about them, too (in the graph of blackness of jean and amount of adventure-having, there's a positive exponential association).
I'm sure you can buy off-the-rack "black" jeans with this sort of patina, but I'm willing to bet that most of the jeans ahead are the product of some good wear and tear. Take a look at how other women have embraced their not-so-black blacks and what they wore them with.