One of the oldest minerals in the world--gemstones, are known to rarely depreciate in value. Usually, supply determines the value of gemstones. For example, compared to other gems, diamonds are low in supply, albeit by limited production or companies trying to monopolize the industry, resulting in them being expensive.

You cannot produce natural gemstones, and therefore start-up costs are also high due to the low supply, however, selling these precious gems can be quite profitable....