Metals : Gold

Gold won't tarnish, rust, or corrode, and though it's very strong, it is also the most malleable of all metals. A single ounce of gold could be drawn into a wire 5 microns in diameter, more than 80 kilometers long.
Pure gold is too soft to withstand the stresses of daily wear, so it is alloyed with a mixture of metals like silver, copper, palladium, and zinc to give it strength and durability. Karatage indicates purity and is noted by a number followed by the letter "k". Traditionally karatage is expressed in 24ths, meaning 18k gold is an alloy of 18 parts gold and six parts other metal. 24k gold is 100% gold with no alloyed metals.