When CV lenses were first released here in the States years ago, they were in the familar black boxes, as they are currently. Between those first early days and now, whenever I traveled outside the States (like to Europe), the same lenses were sold (and seen) in their green boxes...so I assumed it differentiated different markets much like Nikon did with their lens boxes (see below) and they possibly didn't include warranty coverage by the official USA importer at the time of it being manufatured. When a black CV box was opened, a USA importer warranty card is seen, but not with most all green boxes (except for those occasionally small accessories or limited items where costs didn't justify producing a seperate black box).
In the U.S., for the longest time (until recently) Nikon lneses came in gold boxes plastered with images of the front element of many lenses. The lens boxes from outside the U.S., were mostly solid gold and this designated to us here in the U.S., that these were gray market lenses and not accompanied by the USA 5 year warranty and that Nikon USA wouldn't repair those lenses and if some non authorized store in the U.S.A. was selling these solid gold boxed imported Nikon lenses, they were received from an importer outside the U.S., which were often cheaper in price but did not have the U.S.A. warranty.
I assumed this is/was the case with black CV len boxes vs. green boxed lenses....namely the black boxes are official U.S.A. imported CV lenses with USA warranty (except for those occasional low production items that didn't have a black box printed speicifically for them).
Whether black CV boxes are also used for any other markets outside the U.S., I honestly don't know.
Dave (D&A)
Dave