Platinum is generally 95% pure and does not tarnish or lose its rich white luster. Platinum is the heaviest of all the precious metals weighing approximately twice as much as karat gold. Its purity makes it hypoallergenic, perfect for people who are sensitive to the alloys used in gold. Platinum is also known for its strength and pliability, just one gram of platinum can be drawn into a fine wire over one mile long.
Pure 24 karat gold is rarely used in jewellery because it is too soft for frequent wear. Gold is mixed with alloys like copper, silver, nickel, and zinc to give different colours, strength, and durability. Gold's purity is measured in karats, which indicate out of 24 parts how many parts are gold. For example, 18kt gold contains 18/24 gold and 6/24 alloy, while 14kt gold contains 14/24 gold and 10/24 alloy. Gold is traditionally seen in yellow and white colours, but can also be available in rose or green on occasion.
Sterling silver is usually 92.5% silver and 7.5% copper. Silver is much more plentiful than platinum or gold and is much less expensive. It takes on a much higher polish than any other metal, but it does tarnish. The tarnish can be removed, but silver requires much more care than other metals.