Unfortunately the recipe may be bugged. Most patterns that drop off of specific creatures are bind-on-pickup and can only be farmed by those characters that actually have the profession required to learn the recipe. For instance, the pattern for Ragesteel Shoulders can only be looted by blacksmiths. Recipes that can be looted by any character tend to be world drops and do not bind-on-pickup. The plans for the Eternium Runed Blade is an example of this type of item. On the other hand, the design for the Chaotic Skyfire Diamond lives up to its name and doesn't follow the trends already set in WoW. It is not bind-on-pickup, but it drops from specific creatures and only seems to be appearing for jewelcrafters, at least according to the data and comments on Wowhead.
What have your experiences with this pattern been like? I wasn't able to farm it up on any of my characters aside from my jewelcrafter, even after spending quite awhile killing Sirens. Did you experience something similar?