The Diawl bach nymph is one of those patterns that is fast becoming a 'must have' fly in your flybox. It is tied to represent a beetle pattern (the exact interpretation is 'little devil), but it can represent a whole host of acquatic insects that the trout consider as food.
A standard pattern includes a gold rib along the peacock herl body. However, the pattern is often tied with other colours of holographic tinsel, that gives an extra flash in the water. I have taken the holographic theme a little further and tied some with a green rib and a pearl rib. They are tied on size 12 hooks and comprise: two with gold rib, two with red holographic rib and one each with blue holographic rib and one green holographic rib. (Set B).