Why do some Rieslings come in blue bottles?

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.
Dear Dr. Vinny,
Mine's a pretty basic question. I was just wondering, why is Riesling bottled in a blue bottle?
—Anne Marie, New Jersey
Dear Anne Marie,
Actually, most German Rieslings are bottled in green or brown bottles. Traditionally, the color signaled the wine's origin: brown meant Rheingau; green, Mosel.
During the 1980s, some German Riesling producers started switching to blue bottles to distinguish themselves from the rest. Armin Wagner, the export director for Langguth, the firm that owns the German Riesling line Blue Nun, says, "Blue Nun did this change in 1995 mainly to distinguish itself from the brown bottle used before, which had become synonymous for Liebfraumilch [a sweet wine]. Blue Nun is today not a Liebfraumilch but a slightly drier and crisper German Qualitatswein, so the blue bottle was an additional signal to amplify this change."
—Dr. Vinny