See how Bryan's is very very very dark like someone colored on it with a marker, then taco is just like a chocolatey dark color? Look mostly at the faces for comparison. That's clue #1 that Taco isn't a BCL.
Clue #2 is the size of Taco. Like I said BCL are very slow growing species. I think it takes something like 6 years to get them to breeding size.
Clue #3 is a big difference in pattern and background color. Bryan's BCL has thinner straight saddles with clear medallions on the side. Taco has fat wide saddles with a little bit of a widows peak and funky pattern sides.
There is no doubt Taco is a cool looking boa but he is not a BCL. As far as iridescence goes it's kinda hard to pinpoint a color. Some look more blue, some look more rainbow but they are all beautiful