THE STRATEGIC Diamond

At the present time Diamond mines, which are very large-scale enterprises, produce some seven tons of Diamond each year. The Diamond material that is transparent, and of good shape and quality, is used for conversion into decorative GEMS and this amounts to about one ton. The remaining six tons, ill-shaped, of poor colour and aesthetically spoilt by inclusions built in during growth, are consumed in industry, which eagerly absorbs as much as the mines can produce.

Diamond is very scarce, and to produce this seven tons of Diamond over 150 000 000 tons of what is called diamondiferous ore must be hauled to the surface, crushed, treated and sorted. It is thus not surprising that Diamond is costly as raw material alone. Last year (1967) these few tons of mined Diamond fetched about £180 million sterling - a formidable sum indeed. Of this, the one ton of GEMS fetched the major sum; the six tons of industrial Diamond raised many millions of pounds - when synthetic Diamond was added, the value approximated to £50 million.

As Diamond is so very hard, the fabrication of diamond into required shapes is a time-consuming and costly business, and in any case can only be carried out by highly skilled craftsmen. Taking into account the cost of the raw material coupled with the high cost of fabrication, it becomes immediately evident why Diamond GEMS are expensive. Add to this the rarity value of large good-quality crystals and we soon see why particularly large polished Diamonds command fabulous sums.

THE Carat

Diamonds are measured by a unit of weight called the 'Carat', which is one-fifth part of a gramme. The origin of this meas­ure has a most curious history. During ancient times, especially in the Orient, and also in later medieval times, the jewels par excellence used by the wealthy and the great were not Diamonds but pearls and rubies. The principal jewel in terms of quantity was the pearl, fished up from time im­memorial in oysters from oriental seas, and occasionally from river mussels. Pearl valuations were decided with regard both

THE Diamond

to weight, to shape and to colour, the more spherical the more the value. In early days although there were hardly equiva­lents to our customs and excise standards of weights and measures, some standards of weight were an essential to trading. The most famous of these was, of course, the 'shekel' used for silver. Now, as a small but reliable standard of weight for measuring pearls, the wily dealers of the Orient came up with a remarkable solution. The standard adopted had to be at once small, reliable and easily come by, and this they achieved with the 'Carat'. There exists widespread in the Middle East and Levant a tree, the locust tree (ceratonica siliqud). This produces a sweet hard fruit (the locust fruit), which, when dried, has the appearance of a flattened, quite hard, black-looking banana. (When the writer was a boy this fruit was available in the school tuck-shop.) This fruit, which is curved and looks like a horn, has, the Greek name 'Keration' (a horn). Now, the oriental pearl dealers made the striking discovery that the dried brown fairly large seeds inside the dried keration fruit had an extraordinary uniformity in weight. They therefore adopted this seed as the standard of weight ('Carat') for pearls, and soon it was used for all GEMS. This seed weighs almost one-fifth of a gramme, and as there are 28 grammes to the ounce a Carat is slightly less than 1/140 part of an ounce.

We ourselves have demonstrated with a modern precision chemical balance that the keration seeds are really of an astonishing uniformity. Of course, they do differ, but our samples did not differ each to each by more than 1/3000 ounce -a tribute to the sagacity of the oriental traders, to whose crude balances these seeds must have seemed identical in weight. This small weight unit has now been stabilised internationally to what is called the 'metric Carat', precisely one-fifth of a gramme.

VALUES OF GEMS

The value of a Diamond as a gem depends upon several fac­tors, which include size, quality, shape and history (or legend!). As far back as the early 17th century the distinguished French gem expert Tavernier reckoned the value of a Diamond to be proportional to the square of the weight. Strangely enough, with regard to good quality GEMS of medium size, Tavernier's formula almost still holds good. When a gem Diamond is polished into a special shape to give best 'fire' it is called a 'brilliant'. Today, a fine-quality 1-Carat brilliant will cost about £400, whilst the market value for a fine 5-Carat brilliant is about £9000. According to Tavernier's rule the price of the 5-Carat stone would be 52 (i.e. 25) times that of the 1-Carat stone; namely £10 000. This calculated figure is surprisingly close to what in fact one has to pay today.

In striking contrast is the price of the low-grade industrial Diamond, low grade in appearance, nevertheless invaluable for numerous technological applications. A 1-Carat industrial Diamond can cost now some £2, and a pro rata valuation operates for bigger crystals such that the 5-Carat industrial stone can be obtained for £10. Of course, a really large gem-stone can cost a fabulous sum, especially if legend or history be attached to it. Even recently unearthed fine-quality large crystals are of enormous value. In the Premier mine in South Africa there turned up in 1954 a pure-quality Diamond of weight 426 carats. This was cut into a gem of the finest quality, weighing, after shaping, only 130 carats (a little less than 1 oz). Yet this Diamond, now called the Niarchos after its purchaser, is valued at the astounding sum of £714 000!

Legend and history have played their part too in affecting the prices of special individual GEMS. The renowned blue Hope Diamond, probably cut down from one brought from India in the 17th century by Tavernier, weighs only 44½ carats (a mere ⅓ oz). Yet its value when it was presented in 1958 to the Smithsonian Institute in the U.S.A. was assessed at one million dollars! Such valuations are, of course, excep­tional, but they do indicate that amongst those fortunates who have the means, there is still an intense competitive wish to own large and beautiful or historical Diamonds and this is a fact which has persisted throughout the ages.

Many great Diamonds have played surprising parts in his­tory. To begin with, Diamond acquired considerable virtue in the early Middle Ages, not because it was a gem but in fact mainly because it was so hard. Until about a.d. 1300 or so, Diamond was regarded as a magical amulet. It was a precious hard stone and if carried or worn would endow its wearer with a number of 'hard' magical virtues; its powers were strange, numerous and miraculous. The wearer was protected against witchcraft, was made courageous and hardy in battle, was able to control and overpower wild beasts, would not suffer from nightmares, and so on. Only the rich and mighty could afford Diamonds; which were, in fact, very much scarcer then than they are today. All ancient Diamonds came from India, which was the sole source. These were found by scratching the surfaces of gravels in certain diamondiferous regions. Surprisingly large numbers of peasants were engaged in the search for Diamonds. Tavernier in the mid 17th century tells of visits to the Diamond mines of India and of one mine that alone employed the extraordinary number of 60 000 miners, mostly women and children scraping, scratching, washing and sorting. In contrast, we shall see later that today some of the most sophisticated of all modern techniques are used in South Africa in winning Diamond either for use as GEMS or for use in industry.