Hi David,
I (sort of...nobody
really knows
anything about rugs
) know that an apricot-ish shade is achieved by dying in a depleted madder dye bath. I would think that was the process used to produce the particular color in your rug.
About age, I don't mean to be a crank about it. It is just that in order to be able to say with authority that such and such a rug was woven in 1880, it would seem that one should be able to say by contrast what was being woven in 1870, and in 1890. And if the group didn't change its act over the whole period, how can anybody throw 1880 around credibly?
I understand the notion of working out an approximate continuum in one's head after having seen and handled many rugs. But in order to apply that tool, one must assume that the changes (chiefly, degradations) in the product from any one source were uniform in time and spread consistently across the weaving group(s) geographically. However, I suspect that the developmental progress within most weaving groups was irregular in many cases, and often triggered by specific events of which we have no knowledge, such as the initial availability of a particular dye, or dye source; or little surges in rug production within particular groups based on accidental circumstances, also unknown to us. Etc. Nevertheless, one rarely encounters any kind of analysis along the foregoing lines accompanying the attribution of ca. pre-1900 dates to specific rugs.
Sorry about that!
Rich