I have seen size 31 listed as 6.75qt, but they are all smaller than this one. It is also nice and heavy. Based on the style and color, I believe this is from the 1960s or 70s.
There is very little wear to this dutch oven. There is some chipping to the enamel on the underside of the edge of the lid. You can see this in the photos. There is some scratches and scuffs on the body, but they are light.
The inside has some staining, but is fairly clean for the most part. There is some pitting to the handles as well, which is to be expected. The handle of the lid is enameled as well, which I did not see in many others. Please see all pictures for more details.Tall shelf next to desk.