Once in several lifetimes, it may be possible for an average member of the public to glimpse a fabled piece of gemological history. If it is going to happen at present, then the Natural History Museum in London is a strong contender as the place. It is the UK’s principal repository of mineralogical specimens and one of the most visually satisfying museum buildings anywhere.
A single and magical word, “Diamonds” suffices for the title of this most exotic assembly of magnificent stones. Brought together under extreme security in the museum’s newly enlarged temporary exhibitions’ gallery, the exhibition brings together a fascinating mix of historical and rare gems and, in the best traditions of the museum, an easy-to-understand series of displays that explain the intricate physics of the simplest and fourth most abundant of elements in the solar system — carbon.
The star of the show for most visitors is the Millennium Star, a 203.4 carat pear-shaped stone D color and flawless. Cut from a 777 carat rough stone — the sixth largest ‘colorless’ stone ever found — it was finally cut into three pieces after three years study and first shown as the centerpiece at the Millennium Dome in London in 1999. It there became the target of an audacious — and luckily foiled — robbery attempt. It is a simply stunning piece and is a worthy centerpiece for the Diamonds exhibition.
However, the exhibition soon disabuses the visitor of the idea that diamond is simply a white sparkly gem with a breathtaking display of incredibly rare colored — or fancy — stones. On display behind optically perfect but very secure glass, yet close enough to observe in detail, is a collection of some of the rarest diamonds ever found. Pink, blue, blue-green, vivid orange, yellow red and black; all diamonds, all in one place.
Of particular note in the display are the Steinmetz Pink, the Blue Empress and the Orange Flame. A tradition honored over centuries is to name important stones after the owners, modified somewhat in recent times to include less eponymous names.
The Steinmetz Pink is a 59.6 carat stone, oval mixed cut stone very distinctly pink, the color sometimes dimmed by the gem’s scintillation. Internally flawless, it was cut from a 132.5 carat crystal after years of intense study.
It seems at first thought odd to emphasize the study aspect of cutting an important stone. Cutting a diamond though is not a simple task, not just because of its phenomenal hardness, but also because the internal crystal structure of a diamond in its rough state is not always immediately obvious. Few in their natural state take on the familiar shape on the playing card, although planes of weakness — cleavage planes — mimicking that shape exist inside even the most misshapen rough diamond. Finding those cleavage planes to minimize loss of material and maximize the finished size of the gem is the critical esoteric art-cum-skill.
The Blue Empress and the Orange Flame are exceptional gems even by this exhibition’s exotic standards. The Empress was one of 11 in the De Beers Midnight Collection. An intense heavily saturated blue, caused by traces of boron in the crystal lattice, the 14 carat teardrop shaped gem was first displayed in 1999.
The vivid color of the Orange Flame is truly astounding. Only 3.32 carats, it glows brilliant orange with a hint of yellow in the pure white light of the display cabinets with an intensity far beyond what you could reasonably expect for its small size. Even at its relatively small weight, it is still one of the largest ever found, most intense orange stones being less than one carat.
From the small to the — in diamond terms — enormous. The Incomparable weighs in at a cut weight of 407.48 carats and is the third largest cut diamond ever recorded. It is the largest of 15 gems, cut from an 890 carat rough found by a young boy in the 1980’s in the Democratic Republic of the Congo. It is a fancy yellow-brownish kite-shaped gem and is graded as internally flawless.
A very fine example of the classic diamond-shaped stone, which genuinely looks like the popular image of a diamond, is the “616.” Found at the Dutoitspan Mine in Kimberly, South Africa, it is the largest uncut diamond in the world today. One of the many examples of uncut stones in the exhibition, the 616 encourages the visitor to look more attentively at the less glamorous but — for my money at least — the more intriguing side of the exhibition.
The Natural History museum is committed to public education and has commendably kept the faith by mounting an easily understandable section on the genesis and physics of diamond. They have selected some memorable examples of diamond rough from their extensive collections and accompanied them with comprehensive explanatory labels and audio-visual displays in a sophisticated low key but effective series of displays. There is even a small phial of diamond dust and the meteorite it was collected from!
Modern technology has made the production of synthetic diamond a relatively easy process. The process is clearly explained with examples of the various products, from Chemical Vapor Deposition diamonds and polycrystalline diamonds through to large single crystals. To round the section off there are examples of diamonds in industry together with examples of the tools they are used in and video footage of what they can do.
One particularly intriguing tool is a surgical scalpel made from a single optically-perfect diamond grown to the flat shape of the blade. The atomic structure of a diamond crystal allows the edge of the blade to be ground to an edge hundreds of times finer — and therefore sharper — than steel and it never needs re-sharpening. Apart from the cutting qualities, the diamond blade allows light to be channeled into it and because of the optical properties of diamond, a thin line of light shines from the blade onto the surface to be cut immediately below the cutting edge. It has found ready applications in eye and micro-surgery. There is a very simple and, to me, immensely touching display of a few tiny diamond crystals in a small wooden box, accompanied by working notes written in a minute and precise hand. It would be easy to miss, but it is the result of one man’s dedication and most of a lifetime’s ambition.
James Ballantyne Hannay, born January 1, 1855, was a gifted chemist who registered numerous patents. His ambition was to synthesize diamonds. He understood the chemistry of diamond synthesis and after blowing up numerous sets of high-pressure and temperature apparatus, in February 1880 sent a collection of small diamond crystals to Professor Storey-Maskeleyne at the Natural History Museum. He published a letter in the London Times on February 20 confirming that indeed the samples were diamond and Hannay was recorded as the first person to have synthesized diamond. After many examinations of Hannay’s output, it was not until 1967, by which time the production of synthetic diamond was commonplace, that the stones were confirmed at King’s College London as diamond — but natural ones.
Had Hannay cheated? Or had, as one story goes, an assistant got so fed up with the life-threatening explosions in Hannay’s laboratory equipment used in the synthesis process that he placed them in the machine? No one knows for sure. What is certain is that Hannay knew how to produce diamonds and made vast contributions to chemistry and industry along the way. The tiny box of crystals is his memento mori.
For all the technical and cut stone brilliance, it is the jewelry that most visitors go to the exhibition to see, and it is there in profusion. The magnificent Excelsior diamond (cut weight 69.68 carats) the second largest rough ever found at 995.2 carats mounted in a necklace is but one rare example. Another rarity is the Orloff Diamond, a gunmetal grey stone with a chequered history dating back over 300 years and mounted as a pendant.
The jewelry is not all antique or historical. There are striking examples of the “hi-lo” fashion using expensive and inexpensive materials together. One fascinating example is a necklace by Cornelia Rating made with platinum, diamonds and coal. The conceit is ironic — diamond and coal are the same element: Carbon of course.
Notes: The exhibition runs until February 2006, seven days a week. To ensure admission, book on the Internet.
