As you no doubt noticed, the rose gold in the Blu Notte case is Panerai’s proprietary Goldtech, a special alloy with a higher percentage of copper and platinum. In addition to providing a deeper, darker color, it’s also resistant to fading, a nagging problem for watchmakers working with rose gold. Several brands have their own alloys created with colorfastness in mind, most famously Rolex with its aptly named Everose Gold.