The top four gemstones of all time have always been the ruby, emerald, diamond and sapphire. This exquisite Cartier flamingo brooch displays all four. It was a 1940 Easter gift from the Duke to the Duchess of Windsor (nee Wallis Simpson).

These highly desirable coloured gemstones were rare because they came from very few and distant sources. The most prized were the deep red ones like the pigeon's blood rubies from the Mogok mines in Burma. The true ruby is sometimes called the oriental ruby to distinguish it from the spinel ruby which is an entirely different gemstone. The most famous spinel is the Black Prince's Ruby which is prominent on the British State Crown. Back then, all red coloured gemstones were called rubies such was their desirability.

Rulers sought to possess all these rare gemstones for they were a marked display of luxury, and a way of exhibiting their power and might. Cleopatra did it in spades with emeralds. Cleopatra's mines were once the only source of emeralds. After these mines were exhausted, emeralds had to come from Spanish mines in South America. Sapphires have always been a royal favourite, gracing crowns including the same crown mentioned above. The Ancient Egyptians even imported them to place in the burial chambers of their dead. Sri Lanka, is the chief (and oldest) source of sapphires. But cornflower blue Kashmiri sapphires are considered the loveliest.

Today, their relative order of descending popularity has switched to diamond, emerald, ruby and sapphire. What happened? Diamonds were very rare as India was the only source until a few centuries ago. But they were not that captivating until the late 1700s when lapidarists came up with the clever brilliant form of cutting enough facets to really show off their sparkle and fire. The production and marketing of diamonds are also now tightly controlled by the De Beers Company through a diamond cartel. This results in artificially high prices even though diamonds are not that rare. Their 1947 marketing "A Diamond is Forever" campaign was so successful that it totally changed bridal expectations. Different gemstones were favoured for engagements ring before then. But now, four out of every five engagement rings are set with diamonds.

Ernle Bradford (1967). Four centuries of European Jewelry. Spring books.
Michael Bloch (1996). The Duchess of Windsor. Weidenfeld & Nicolson.
Victoria Finlay (2006). Jewels : A secret history. Ballantine Books.
Sotheby's Auction of Magnificient Jewelry, 1987.