It is important to realize that tartan is much more of an art form than a science. It is a visual art. And to that end, what matters most in distinguishing one pattern from another is the visual similarity.

I have an old MacGregor kilt hanging in my closet. It's probably over 80 years old at present. It is quite obviously the MacGregor tartan. In fact, here I am wearing it, standing next to Sir Malcolm MacGregor, chief of the clan.


No one, not even the chief, would say the tartan I am wearing was anything other than Clan MacGregor.

Just for fun one time I decided to take a thread count off of this kilt. I compared it with every variation of the MacGregor tartan, official and otherwise, on record with the Scottish Tartans Society, who at the time had the largest available tartan database. (This was years before the National Register came about). The thread count on my kilt matched none of them. Not a one.

And I do not simply mean a difference of ratio. It was not as if the number of threads had simple been doubled, or trebled. The number of threads for each element in the tartan was off by a slightly different proportion to that of other design elements in each recorded version. Numerically, my tartan was quite different. But visually...? It is quite obviously a MacGregor.

So the definition of a tartan is much more subtle than being a strictly defined thread count, from which no variation may be made. It is the overall design and color, and is a very subjective matter. Does it look like the correct tartan? Or doesn't it?