On-camera, the 11th Doctor’s “anniversary” waistcoat usually appeared to be dark, solid, warm, purple.
Even during fairly close shots on Blu-Ray, the fabric often looked solid purple.
This was often the case in behind-the-scenes footage, as well.
However, hints of the waistcoat fabric’s weave were occasionally visible, if one looked closely enough …
In fact, in some of the high-resolution publicity photos for the specials, we could clearly see that the fabric was, in fact, a lovely plaid.
This behind-the-scenes photo possibly gives us the best look at the fabric’s weave.
A few years ago, Steve Ricks found some of the original fabric and posted some scans of it on his blog, which you can check out here:
http://www.11thdoctorcostume.com/2014/04/fabric-friday-day-of-doctor-waistcoat.html