Opal was released in 2002 by Germany's Hüll breeding institute, one year after Saphir and part of the same general cluster of early-2000s German aroma-hop releases aimed at giving brewers a range of subtly different noble-adjacent options rather than a single fixed Hallertau character. Its parentage traces back through Hallertau breeding stock, though it sits at a somewhat higher alpha acid than either Saphir or true Mittelfrüh.
At 5.5-8.5% alpha acid, Opal is more genuinely usable for a moderate bittering charge than its lower-alpha German siblings, while retaining a mild spice and fruity aroma that keeps it in the same general noble-adjacent family as Hallertau Tradition or Perle. It doesn't carry a single dramatic distinguishing trait, functioning instead as a flexible, moderate-alpha German aroma hop. Opal's alpha sits comfortably between the very-low-alpha noble hops like Saphir and the considerably higher-alpha American varieties covered elsewhere on this site — the IBU calculator will show exactly where an Opal-based charge lands between the two. Hallertau Tradition is the closer substitute given a similar alpha range and general character, while Perle offers an alternative with its own minty edge if that's an acceptable trade. German lager and traditional ale styles use Opal wherever a dependable, moderate-alpha German hop is needed without a single dramatic aroma trait to build a recipe around. Opal's alpha floor sits above both Spalt Spalter's and Tettnanger's ceilings, making it one of the more genuinely usable German aroma hops for an actual bittering charge rather than a purely late addition.