Brindle is actually the correct term. It became known as Cumberland after the Dunhill Cumberland line of pipes became popular. They came with Brindle pipe stems, thus Cumberland became synomous with the stem. Much like Klenex, the brand vs Tissue, the item.
Traditionally it is black and red swirled together, but lately I have been seening many new iterations that are just wonderful. They have blue, brown and green that I have seen, all swirled with black. I am aure there are probably more of them.