While all coins have value, which directly correlates to the variance in gold prices, the most popular gold bullion coins offer the best investment opportunities. The best investment grade gold coinage may vary in design, but they generally increase or decrease in value at the same pace. The purest 24k .9999 fine or .99999 fine coins suggest better value in markets when supply of coins exceeds their demand. The Royal Canadian Mint has the reputation for having the best value for purchasing gold bullion coins.