Coloured gem market mysterious and poorly understood

The coloured gem market — sapphires, rubies and emeralds — is just as valuable as the diamond market.

At a time when many investments offer low returns, many investors will fill a bag with precious stones and hope they will be worth a fortune some day.

Check this chart about the rising prices of gemstones.

Unlike diamonds, though, the $10 billion coloured gems market is mysterious and poorly understood.

This Wall Street Journal video illustrates the issues.