The Indian stamp market continues to warm, although as yet it has not become as white-hot as China's, and there are still some areas which remain neglected.
In 1957, Portugal issued a set of eight stamps for its colony, picturing a map of its territory in India (Scott #552-59). 50,000 sets were issued, and Scott '14 prices the unused set at $11.75 .
The set has multiple market appeal to collectors of Portuguese India, Portuguese Colonies, and India, as well as to Map Topicalists, a small but growing cohort.
Those interested in learning about investing in stamps should read the Guide to Philatelic Investing ($5), available on Kindle and easily accessible from any computer.