Black Irish Tartan?

[MacMullen]

This is from Wikipedia. I don't know how accurate it is, but here's what they have to say on the topic of the Black Irish:

Popular theories
Despite the popular theory that the "Black Irish" are descended from survivors of the Spanish Armada, the genetic contributions of this group were actually fairly insignificant, since most Armada survivors were killed on the beaches, and most of the remainder were able to eventually escape Ireland after a short time. A few Spanish soldiers ended up serving as armed retainers for the Irish chiefs O'Rourke, Sorley Boy Macdonnell, and Hugh O'Neill, Earl of Tyrone, so they might have lived in Ireland long enough to father children, but they were very few in number.

There have also been theories linking the "Black Irish" to the presence of Phoenicians in Ireland during ancient times. However, in the Irish language dubh is the word for black, while gorm (literally blue) is the word for black-skinned. Because of this distinction, many doubt that the Irish would have used the English word "black" to describe their skin colour.

However, no distinct population group of "Black Irish" actually exists, or has ever existed. The myth of the Black Irish was coined in America to explain the existence of Irish people whose appearance did not conform to stereotypical images of what Irish people look like.

Other uses of "Black Irish"
The term has also been used to refer to the offspring of Irish and African slaves in the Caribbean, and many Irish surnames can still be found in the region. Montserrat is the Caribbean island with the greatest levels of Irish heritage as it was forcibly settled by the English crown using Irish slaves. These Irish slaves were eventually replaced by West African slaves who took on the names and surnames of the prior inhabitants, much as African slaves in the United States took on the names of their owners.

In the United States, people with Native American or other dark-skinned ancestry may historically have called themselves "Black Irish", "Black Dutch" or "Black German" to explain their coloring.