Here is a little information on the different precious metals. Most precious metals are alloyed to create different colours and hardness. The hallmark will show the precious metal content and is always out of a thousand parts.
Is white in colour and hallmarked 925. Pure silver is very soft. Silver often tarnishes over time and can also oxidise on certain skin types. The silver will appear black or grey when this occurs. Silver is a great conductor of heat. It is rarely set with expensive gems for these reasons.
Pure gold is 24ct and very rich in colour. As with silver it is very soft in its pure state. It is alloyed to create different colours and hardness. For example, Palladium, silver and other white metals are added to create white gold. The higher the palladium content the whiter the gold becomes. Copper and other metals are amalgamated to produce rose gold. 9ct is hallmarked at 375 14ct is hallmarked at 585 18ct is hallmarked at 750 22ct is hallmarked at 916
The higher the carat number the higher the gold content and the softer it becomes; yellow gold will become richer in colour. White Gold is often Rhodium plated to give it a whiter appearance.
Is a pure metal and of the same family of metals as platinum. It has recently been recognised by the assay office and is now hallmarked at 950. It has a very similar colour to platinum and a great alternative as it is less expensive being closer to the price of 14ct gold.
Is the rarest of the precious metals and therefore fetches the highest price. It is white in colour. Platinum is hallmarked at 950. Platinum also has an extremely high melting temperature at 950°C.