Silver and Platinum are both among the very rare metals in the world; this explains why they're mostly used, especially in the making of jewelry. Both silver and Platinum are very similar at sight, but it is just at that point of sight that their similarities end. Silver is a soft metal which is commonly melded with other metals such as copper, nickel, and Zinc in order to increase the durability of the silver. For example, Silver Jewelries wear out of shape with time and changes color to black when in contact with moisture, that is the reason regular maintenance is needed to keep silver shining.
Platinum is a very strong metal, unlike silver; it has a very high melting point that does not rust, changes color, or wear out over time. This explains why it is so special and the reason for it being the most expensive of the precious metals. Platinum is also alloyed with other metals such as copper, palladium, cobalt, iridium, and ruthenium.