Over 95% of the world's annual natural pink diamond supply is mined from one single source: Rio Tinto's Argyle Mine in Western Australia. The mine has been in operation since the early 1980's and is schedule to completely cease all mining by 2020.The mine has been the most significant source of rare pink diamonds producing more than 90%-95% of the world's supply.

As with all diamond mines, the Argyle mine has a limited lifespan. Rio Tinto confirm that by the end of 2020 it will no longer be economically viable to continue mining operations.The closure will be a major milestone and its significance has not been lost on savvy investors. Like all assets, the diamond market follows the laws of supply and demand. As such, when Argyle does close, the supply of pink diamonds will be even more limited.This closure positions the pink diamond as an investment opportunity offering significant capital gains in the medium to long term.

The primary investment appeal of pink coloured diamonds is their potential for capital gain. Over the past decade and more, anyone that has purchased a pink diamond has seen a significant appreciation in the value on their investment. Strong performance is not limited to the last decade, with pink diamonds delivering exceptional returns over the last 20 years.

Pink diamonds have outperformed all major asset classes and commodities. Pink diamonds have shown very good stability and consistency of performance over the long-term and have been considered an important holding for strategic investors. Since formal records regarding diamond pricing were first kept at the beginning of the 1970's, prices for pink diamonds have appreciated between 10% to 20% per year on average across all sizes and categories. Pink diamonds do not demonstrate the volatility we see in equity markets, commodities or indeed precious metals.