Official stamps were issued for use by various international organizations headquartered in Geneva. The earliest of these organizations were associated with the League of Nations, while the later issues were for UN organizations. I favor all of the scarce and undervalued stamps issued for these international organizations. As these issues are all overprinted Swiss stamps, much of the current demand for them comes from collectors of Switzerland. A far greater proportion of the Swiss population are stamp collectors than are Americans, and the level of interest there is comparable to that which exists Germany.
In 1950, a set of 8 stamps was issued for the International Organization for Refugees (Scott #6O1-8). 24,000 sets were issued, and Scott '11 values the unused set at $88.- ($150.- for NH). I view the set as a conservative investment, which should do well over the long-term.
Switzerland, a nation of 7.8 million people,is one of the richest countries in the world by per capita, with a nominal per capita GDP of $67,384. The country experienced slow growth in the 1990s and the early 2000s, and was hurt by the global financial crisis, which has resulted in greater support for economic reforms and harmonization with the European Union.
Those interested in becoming part of an international community of stamp collectors, dealers, and investors are welcome to join the "Stampselectors" group at Facebook. The group hosts lively discussions concerning stamp investment and practical aspects of collecting, and provides a useful venue for those who wish to buy, sell, or trade stamps.