I would definitely agree with that match. There is a bit of difference in terms of color correction in the scans, but I think the telling sign is the underlying red hue present in both the Chesterfield Fire Opal and the Diamine Orange.
Like I said, this ink gets on my nerves hardcore. But, it was otherwise a nicely behaved ink and I can't complain about it except for the my bias against the color. You also get a pretty nice discount buying the Chesterfield vs Diamine, at $10/100 mL for Chesterfield and $15/80 mL for Diamine. Of course, neither of those prices is outrageous, but why not save a few dollars if you can? The biggest difference is that the Chesterfield comes in a plastic bottle rather than glass, and my experience with those bottles is that the neck is quite narrow. Thus, it might be best if you have another container to decant into, or you are planning to syringe fill.
This ink sample was given to me as a gift and I am not being compensated for this review in any way. All opinions expressed above are my own, and you are free to disagree if you like.
PS - I've decided to start taking my quotes that I put in reviews from my current favorite songs, so that you can all see what horrible taste in music I have. Anyway, I'll try and remember to put a link to the song referenced at the bottom here, in case you want to take a listen. They won't necessarily relate to the ink being reviewed, so sorry for any confusion there.