Rare gems still dazzle

Establishing rarity is of utmost importance to owners of fine diamonds and gemstones. Exquisite diamonds and coloured gemstones of extraordinary quality or size will always be in demand. In addition, like most memorabilia, if a famous person wore, bought or even sold it, the value jumps significantly.

That is why when professionals talk about the world's most significant diamonds and gems, they have such precise descriptions, which clearly denote the gems' place in the hierarchy of jewels. Qualifications can include the largest of a certain cut, the largest of a certain colour, the most internally flawless of a certain size, and so on. With these superlatives come bragging rights to being the world's best, with values to match.

Next month, one of the most historic diamonds, the Beau Sancy, will be up for auction. Passed down by the royal families of France, England, Prussia and the House of Orange, the 34.98ct modified pear double rose-cut diamond has witnessed 400 years of European history and will no doubt make headlines when it is sold on May 15 by Sotheby's.

In recent history, some notable diamonds and gems have qualified within the parameters of fame and perfection laid out by auction houses and gem graders. Here are a few with intriguing stories to match.

First up is the Hope Diamond. Many people falsely believe that the 45.52ct diamond is the largest in the world. It is not, nor is it an internally flawless diamond. The largest blue diamond is a 51.84ct blue round brilliant once handled by Harry Winston that is on display at the Smithsonian Museum in Washington DC. The Hope Diamond takes the honours as the largest fancy dark greyish-blue diamond and over the years has attracted stories that it cursed successive owners as it moved from India to France, Britain and the United States.

The Golden Jubilee is the largest faceted diamond in the world, weighing 545.67ct, and was presented to King Bhumibol Adulyadej of Thailand for his golden jubilee in 1997. It is described as a fire rose cushion cut and its story is reminiscent of the ugly duckling.