According to James Bond author Ian Fleming, diamonds are forever. For Marilyn Monroe in the film version of “Gentlemen Prefer Blondes,” they were a girl’s best friend. But for collectors of fine jewelry, diamonds are the sparkling pinnacles of desirability. Indeed, the diamond’s role as the stone of choice to crown an engagement ring is a testament to both the appeal of diamonds in the eyes of newlyweds, as well as the brilliant marketing of De Beers, the cartel that tightly controls their distribution. Still, diamonds have not attracted all this attention for no reason. They are the world’s hardest mineral, a perfect 10 on the Mohs scale of hardness that goes no higher. Jewelers have long admired them for their crystalline clarity and brilliance, which is a technical term for the light reflected from a gemstone's interior. Jewelers will also speak of a stone’s dispersion, or fire, which refers to the glints of various colors produced as light passes through the gem, or luster, which describes the light bouncing of its exterior facets. While most diamonds are colorless, rare impurities in these carbon crystals can produce “fancy” gems in shades of red (the rarest variant, caused by the introduction of hydrogen atoms), blues and grays (boron), and yellows and pinks (nitrogen produces the most common of the colored-diamond rarities). Though diamonds have been mined and fashioned into necklaces, bracelets, earrings, pins, and other pieces of fine jewelery by numerous cultures for thousands of years (some of the earliest references to the gem come from India), the art of cutting diamonds is relatively new. Until about the 13th, diamonds were minimally cut. Jewelers essentially polished their diamonds to shape the gems and make their surfaces sparkle. The earliest cut appeared around this time. This was the table cut, which consisted of a cleaved facet at the top of the gem, a smaller one called the culet at the stone’s base, plus a ring of eight more cuts around the gem’s sides. In this example, the crown of a table-cut gem would include the table plus the four facets that slope down from the table to the edge of the gem, or girdle. The gem’s pavilion are the four bottom facets that slope up from the culet. Table cuts were the state of the art until the beginning of the 17th century, when jewelers devised the rose cut. Unlike table cuts, which gave diamonds a great deal of depth, rose cuts had flat bases or backs, allowing diamond cutters to use thinner, cabochon-like stones that only needed faceting on their crowns. A century later, so-called old cuts revived the table-cut form, albeit with 58 facets instead of less than a dozen. Diamonds cut in this manner are reknowned for their fire. The precursor to the brilliant cut, the Mazarin, had been around since the 1600s, but it wasn’t until 1919 that the modern brilliant cut was devised. Its inventor was a Belgian diamond cutter named Marcel Tolkowsky, who changed the shapes and locations of the old cut’s 58 facets to bring out a stone’s brilliance as well as its fire. Victorian and Edwardian jewelers used diamonds with rose cuts and old cuts with equal enthusiasm, depending, of course, on the market for their jewelry—rings with rose-cut diamonds were especially popular among the growing middle classes. The demand for diamond jewelry in the late 19th century coincided with imports of diamonds from South Africa. Until then, India had been England’s largest supplier, and was famous for stones such as the Hope Diamond (now in the collection of the Smithsonian) and the Koh-i-Noor. At last report, that legendary, some say cursed, diamond was still anchored in Queen Elizabeth’s crown.