For students of marketing, diamonds represent the ultimate triumph. Take a mineral that can be found in relative abundance (despite protestations to the contrary), persuade vast numbers of people that buying one will guarantee eternal happiness or at least make them appear rich and attractive, artfully obscure the more sordid details about diamond use by rebels and despots, and you have created a perpetual money-making machine, at least for those at the top.

This is the successful recipe used by De Beers, which laid the foundations for today’s global diamond industry just over a century ago in South Africa. And it is faithfully followed in “The Nature of Diamonds”, an exhibit at the Royal Ontario Museum put together by the American Museum of Natural History and sponsored by De Beers Canada.

It is understandable that De Beers wants to present the most freshly scrubbed face of the diamond industry to the world. Its corporate survival depends on perpetuating multiple myths. The Royal Ontario Museum is another matter.

While the museum’s director, William Thorsell, has described the exhibit as “extremely comprehensive”, it is anything but. Much like the Michael Lee-Chin crystal in which it is housed, the exhibit is missing important aspects, presumably left off because they spoil the overall effect. (Guttering over the main entrance to hold back drips, in the case of the crystal; a broader discussion of the part diamonds play in conflict, in the case of the exhibit.)

The myth-making begins at the very first information panel, which states that the diamond is “exotic and rare”. This used to be true. India was the only known source before the 6th century AD and remained the main global supplier until the early 1700s, when diamonds were discovered in Brazil. Such limited supply turned diamonds into coveted possessions for the Romans, the Persians, the Moguls, the Ottoman Turks, and European royalty.

Diamonds were credited with medicinal attributes—curing insanity and repelling black poisons, according to De lapidibus, a medieval treatise on gems. They were also favoured by royalty as ostentatious displays of wealth, illustrated in the exhibit with the museum’s own portrait of Marie de Medici, Queen of France from 1573 to 1642.

Yet in a different part of the exhibit, there is a chart showing how diamond production has soared in the last 50 years from less than 10 million carats at the start of the last century to an estimated 170 million carats in 2007. Since the Brazilian discoveries of the early 1700s, major production spread to South Africa (1870), Namibia (1909), the Democratic Republic of Congo (1917), Angola (1921), Russia (1960), Botswana (1970), Australia (1981), and finally Canada (which in 2007 was the third largest producer by value and the fifth by volume). It is hard to call something now mined in 27 countries and widely available “exotic and rare”.

De Beers has been adept at managing this deluge of diamonds. From the company’s inception in 1888, it attempted to control world supply. On the demand side, it worked at persuading couples that diamonds were a symbol of love. The memorable slogan “a diamond is forever” is the product of the company’s successful collaboration with N.W. Ayer, a New York advertising agency, which began in 1938. Similar tactics were used in Japan in the 1960s. China is the new frontier.

Much of this opulent history is documented in the exhibit, along with corporate efforts to link diamonds with movie stars and celebrities. Among the glittery baubles on display are chunky bracelets owned by Mae West and Joan Crawford, a dangly shoulder brooch owned by Elton John, a pair of substantial gold, silver and diamond bracelets given by “Boss” Tweed, a famously corrupt New York politician, to his daughter, and a brooch once owned by Millicent Rogers, heiress to the Standard Oil fortune.