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.
Precious stones are the most beautiful and valuable of all the gemstones. Their colors are vibrant, translucent and brilliant. These natural crystals are also durable, but at the same time rare, and they can be used to create both jewelry and accessories.