To produce a single ounce of platinum, a massive 10 tons of ore must be mined. For many years Japan was the largest market for Platinum but North America is catching up fast. Europe is next. Platinum cost more because it is much more pure than gold and it is heavier. Platinum is more dense than gold which means it wears better than gold.
Platinum causes no allergic reaction with the skin which the alloy in gold can with some people.
Platinum also will not tarnish. Platinum-Cobalt alloy was developed around 1975 and has been used extensively in Europe and Japan for jewelry. This mix when cast will show less porosity than the Iridium or Ruthenium mix. Iridium mix is 900 pure Platinum. More resistant to damage and wear.