Platinum, used widely in vehicular catalytic converters and for jewelry, isn't quite as major an investment metal as gold or silver. Nevertheless, this metal can be a good investment. Historically, its price has been above that of gold, though gold has outperformed platinum in recent years. Platinum's main advantage is the fact that, because it isn't a major investment metal, it isn't subject to the same spikes going into down markets that silver and gold are vulnerable to. Instead, its price tends to be more stable across different market conditions.
The characteristics of palladium, and market for this metal, are more or less similar to those of platinum. Palladium is also used in automotive manufacturing, though less commonly in jewelry than platinum. Generally, the prices of these two metals track each other quite closely. Even though platinum and palladium are very similar, the latter is often used by precious metals investors to add an extra layer of diversification to their portfolios.