Ruby / Corundum is a crystalline form of aluminum oxide (Al2O3) typically containing traces of iron, titanium, vanadium and chromium. It is one of the naturally transparent materials, but can have different colors when impurities are present. Transparent specimens are used as gems, ruby if red and padparadscha if pink-orange. All other colors are called sapphire, e.g., "green sapphire" for a green specimen. Because of corundum's hardness (pure corundum is defined to have 9.0 Mohs), it can scratch almost every other mineral.
Rose Gold gets its rosy tint by mixing copper with gold. The ratio of gold to copper is usually 3:1, but varying percentages can be used as well, the intensity of the color differs according to the ratio of gold and copper. Jewelry with rose gold plating gives off a quality of elegance and femininity.