DIAMONDS i~á1 ~....----, , Some of lthe earliest\ diamonds known carne from India. In the eighteenth ,~

century they were found in Brazil, and in 1866, huge deposits were found near .aKimberley in South Africa. Though evidence of extensive diamond deposits has V>

recently been found in Siberia, the continent of Africa still produces nearly all the ~w~rld's supply ofthese stones. . ~ .

~- '7-. The most valuabl diamonds are large, individual crystals of pure crystaIlline ~carbono ess perfect forms, known as 'boart' and 'carbonade=are clusters oPiiny ~crystals. Until diamonds are cut and polished, they do not spallie like those you see

~L on a ring - they just look like small, blue- re stones.~-~·;;6:-~OUSrh~ ::?, In a rather crude form, the cutting and polishing of precious stones was an art

~ known to the Ancient Egyptians, and in the Middle Ages it became widespread innorth-west Europe. However, a revolutionary change in the methods of cutting andpolishing was made in 1476 when Ludwig Van Berquen of ~es in Belgium inventedthe use of a swiftly revolving wheel with its edge faced with fine diamond powder. Thename 'boart' is given to this fine powder as well as the natural crystalline materialalready mentioned. It is also given to badly flawed or broken diamond crystals, uselessas jewels, that are broken into powder for grinding purposes, the so-called 'industrial'diamonds.

~ 4 Diamond itself is the only material hard enough\ to cut and polish diamonds -~ ~hough recently, high-intensity light eams ea e asers have been developed which

bore holes in them. It may be necessary to split or cleave the large stones before theyare cut- and polished. Every diamond has a natural line of cleavage, along which itmay be split by a sharp blow with a cutting edge.~y --,.S A fully cut 'brilliant' diamond has 58 facets, or faces, regularly arranged. Forcutting or faceting, the stones are fixed into ~holders and held against a wheel,edged with a mixture of oil and fine diamond dust, which is revolved at about 2,500revolutions a minute. Amsterdam and Antwerp, in Holland and Belgium respectively,have been the centre of the diamond cutting and polishing industry for over sevencenturies.

~Coe..r---- " The jewel value of brilliant diamonds depends greatly on their color, or 'water'~ as it is called. The usual colors of diamonds are white ellow, brown, green or blue-

white; the blue-white brilliants are the stones of he 'finest water and so command the(lllghest price;3 During their formation, some diamonds absor metallic oxides from thesurrounding rocks and take on their color. Thus black, red and even bright pinkdiamonds have occasionally been found.

~~ 7 The trade in diamonds is not only in the valuable gem stones but also in the~ ~ndustrial diamonds mentioned above. Zaire produces 70% of such stones. They are

fixed into the rock drills used in mining and civil engineering, also for edging bandsaws for cutting stone. Diamond-faced tools are used for cutting and drilling glass andfine porcelain, and for dentist's drills. They are used as bearings in watches and otherfinely balanced instruments. Perhaps you own some diamonds without lmowing it - inyour wristwatch!

10

ercises"ocabu lar'y.

F- d he following words in the passage and select the meaning you think most likelyLO correspond among the choices given.

l. faced o )a) opposed J! - .® Stl-r.fa.effl'lGo I./~)c) decora ted .

2. flawed@) imperfectly formedb) liquide) badly finished

3. cleavea) move® break

e) cut with sharp knife

0/<..

4. faceting~ setting in rings

CE2> surface polishinge) mounting

5. tahe on~ continueQ2)~~

e) fight

6. finea) paymentb) soft

@ high quality

Missing word summary.Fill in the number blanks from the selection of words given below. The correct choiceswill complete the sense of this summary of the reading passage.

At~+ (1) diamonds have been found in India, Brazil and Siberia, .most of them

come from the African continent. Single large crystals of pure crystalline carbon are

the most v•....Jv.aM. (2) kind, although they do not sparkle ~ (3) they are cut

and polished. The art of cutting and polishing diamonds has been known l {Ii\.Ce

(4) the time of the Ancient Egyptians, but it was not until 1476, wi+k- (5) the

invention of Ludwig Van Berquen's _~Q¡4·'1/.t;~{mthat the modern art of precisión

polishing developed. The color or 'water' of a diamond ckuht.zA (7) its value, though

flawed diamonds are widely used in i~Rv¡ (8) as well as in delicate instruments

such as watches.

1. a) Because2. a) common3. (@ until4. a) before5. a) before6. a) diamond dust7. G) decides8. @ industry

ÉL HoweuerQJ valuable

~

afterb sinceb with

polisliing wheelb) reducesb) jewellery

@Althoughe) colorfulc) aithough.c) along withe) toc) 'boart' crystale) increasese) Zaire

Text and exercises adapted [rom: Mosback, G. & Mosback, B. (1979). Practical Faster Reading: AnInterniediate / Aduanced Course in Reading tuui Vocabulary. Cambridge Englisli Language Learning, pp. 21·24.