Iron is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Pure iron is relatively soft, but is unobtainable by smelting. The material is significantly hardened and strengthened by impurities, in particular carbon, from the smelting process. A certain proportion of carbon (between 0.002% and 2.1%) produces steel, which may be up to 1000 times harder than pure iron.
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.