Please remember that the terms "Ancient" and "Weathered", when referring to versions of Tartans, are used predominantly by the weaver Lochcarron.

Marton Mills uses the term "Muted" for some of their alternate versions.

Other weaving companies have other names for their versions of the exact same Tartan.

The colors used when weaving Tartan are not usually determined by the Thread Count. When designing Tartan we use letters for the color. "B" means Blue. "R" means Red.
We don't normally specify which color Blue or Red.

The whole idea of getting the exact colors you want is actually very new. It used to be all up to the weaver and what colors they liked or had in stock.

I have swatch books here in the shop from a wide variety of weavers and each one is very different. In fact I just looked and find at least seven different MacDonald of Clanranald Tartan versions.

So, when searching for a particular version of a Tartan the name is a dead give away which weaver the fabric was made by.

If I see a Tartan I don't recognize and ask the wearer what Tartan it is...and they reply...XXX weathered...Then I know that the fabric was probably woven by Lochcarron.