Coloured stones with a past.

For centuries this 352-carat red stone was called a ruby. It is a spinel, polished rather than faceted, and inscribed with the names of Mughal and Persian rulers who owned it, including Jahangir, Shah Jahan, Farrukhsiyar and Nader Shah. The connection to Timur himself is now considered a later invention.

It was shown at the Great Exhibition of 1851, then presented to Queen Victoria by the East India Company. Garrard set it in a gold and diamond necklace in 1853, and it remains in the Royal Collection.

At 563 carats, this greyish-blue star sapphire from Sri Lanka is the largest gem-quality star sapphire known. Its star is created by fine needles of rutile inside the stone, and it shows on both sides. J.P. Morgan gave it to the American Museum of Natural History around 1900.

In 1964 it was stolen from the museum in a celebrated heist and recovered the following year. It is on display in New York today.

A 37.82-carat Colombian emerald from the mining area around Muzo, prized for a deep, velvety green and unusual clarity. Tradition holds that it was the centrepiece of a necklace belonging to a Maharani of Baroda.

It was later recut and set by Harry Winston in a ring surrounded by sixty pear-shaped diamonds. O. Roy and Claire Chalk gave it to the Smithsonian in 1972, where it is shown near the Hope Diamond.

Provenance, treatment and origin are the three questions behind every coloured stone. Provenance is who owned it. Treatment is what has been done to improve it, such as heating or filling. Origin is where it was mined, which a laboratory can often determine from the stone's chemistry and inclusions.

A famous stone has all three written down. A stone you buy should too.