Marcia Pointon - Rocks, Ice and Dirty Stones

ROCKS, ICE
AND
DIRTY STONES

DIAMOND HISTORIES

MARCIA POINTON

REAKTION BOOKS

Published by Reaktion Books Ltd
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www.reaktionbooks.co.uk

First published 2017
Copyright Marcia Pointon 2017

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No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers

Page references in the Photo Acknowledgments and
Index match the printed edition of this book.

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eISBN: 9781780237985

A S EVERY ELEMENTARY CHEMISTRY student knows, diamonds are constituted of pure carbon (C) formed at conditions of high pressures and temperatures within the Earths mantle at depths of approximately 140 km and below; they are brought to the surface by eruptions of ancient volcanoes, which probably destroy the vast majority of them. Natural diamonds extracted from mines (illus. 1) are, therefore, geological survivors. This knowledge of diamonds chemical properties is, however, relatively recent. For centuries savants baked, boiled and plunged precious stones into acid in an attempt to discover what they were made of. But in any case, to know that coal and diamonds are constituted of identical atoms is to say rather little. It is the idea that something deemed so beautiful and precious is identical to a substance that is dirty, black and, until the Clean Air Act of 1956, used to heat homes and produce energy throughout Britain, that is startling and that grips the imagination (illus. 2). Since the early nineteenth century, the blackness of coal might be said perpetually to cloud the fabled luminosity of the diamond, casting a sinister shadow and fostering superstitions that have made readers of novels and spectators of films tense with anticipation. Most recent among these is Anthony Doerrs Pulitzer Prize-winning novel All the Light We Cannot See. For, while De Beers and other jewellers, not least high street companies, work hard and largely effectively to persuade customers that the gift of a diamond is a prerequisite to a successful relationship, or to its continuation, the idea that diamonds are cursed, bring bad luck and engender destruction of individuals and nations underpins a swathe of fiction and film.

3 Roman ring set with a diamond.

Pliny the Elder was born in late 23 or early 24 CE and died in the eruption of Vesuvius in 79 CE. Along with the Greek Theophrastus (c. 371c. 287 BCE) he is the most significant recorder and analyst of minerals prior to the Renaissance, and the observations and definitions in his chapters on stones in the Natural History not only formed the foundation of medieval writing on minerals and precious stones but are found underpinning lapidary studies as late as the eighteenth century.

SOME OF THE OUTSTANDING PROPERTIES OF DIAMOND

4 Diamond in its matrix, Kimberley, 1890.

Like other gemstones, diamonds were understood by medieval and early modern scholars as microcosmic and therefore as capable of interacting with the human body. Pigments were (and still are) made from gems like lapis lazuli and they provide the measure and much of the vocabulary for colour: think of emerald green and ruby red. Stones had symbolic qualities and virtues; they were valued for their medicinal and prophylactic properties. Impurities in a diamond can turn it into a blue or pink stone but generally diamonds are colourless. On the other hand, as well as being harder than any other known material, they give off light and refracted colour even in their natural state (illus. 4); when polished they give off a lustre. As Thomas Nichols wrote in 1659:

The true Diamond is the hardest of all other stones, without colour, like unto pure water transparent: and if it have any yellowness or blacknesse, it is a fault in it. This property it hath, that it will snatch colour and apply it and unite it to itself; and thus will it cast forth at a great distance its lively shining rayes, so no other jewell can sparkle as it will.

Lapidaries depended heavily on Pliny and over the ages the same truths and myths are repeated. The idea that diamonds invincibility yields to soaking in the warm blood of a goat, as reported by Pliny, is reiterated by Marbodus and repeated by Camillus Leonardus (or Camillo Leonardo) in 1502 in Speculum lapidum, translated as The Mirror of Stones in 1750.diamonds was enduring (and not without foundation, given the chemical composition of certain common remedies in todays pharmacy).

The physical properties of the diamond, as well as its outward form, have been a source of great fascination. Europes expansion of trade, its development of mining and its discovery of new sources of mineral wealth was accompanied by, and stimulated through, new knowledge about minerals and their extraction. Anselmus Botius de Boodt, a Bruges-born doctor who was medical adviser to the Habsburg court of Rudolf II and who therefore had access to the precious stones in the Habsburg treasury, introduces a note of scientific scepticism into his many times reprinted and copied book Gemmarum et lapidum historia (1609); he suspected but could not prove that diamonds might be destroyed by extreme heat. A famous historical experiment was carried out in 1694 in the presence of Cosimo III, Grand Duke of Tuscany. Using a powerful burning glass, the Florentine academicians managed to obtain a high enough temperature to burn away a diamond. Experiments on diamonds by natural philosophers like Robert Boyle, who published his