Diamond itself is the only material hard enough to cut and polish diamonds--though recently, high-intensity light beams called lasers have been developed which can bore holes in them. It may be necessary to split or cleave the large stones before they arc cut and polished. Every diamond has a natural line of cleavage, along which it may be split by a sharp blow with a cutting edge.
A fully cut 'brilliant' diamond has 58 facets, or faces, regularly arranged. For cutting or faceting, the stones arc fixed into copper holders and held against a wheel, edged with a mixture of Oil and fine diamond dust, which is revolved at about 2,500 revolutions a minute. Amsterdam and Antwerp, in Holland and Belgium respectively, have been the centre of the diamond cutting and polishing industry for over seven centuries.
The jewel value of brilliant diamonds depends greatly on their colour, or `water' as it is called. The usual colours of diamonds are white, yellow, brown, green or blue-
Surrounding rocks and take on their color. thus black ,red and even bright pink diamonds have occasionally been found.
The trade in diamonds Is not only in the valuable gem stones but also in the industrial 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 band saws for cutting stone. Diamond-faced tools are used for cutting and drilling glass and fine porcelain and for dentists' drills. They are used as bearings in watches and other finely balanced instruments. Perhaps you own some diamonds without knowing it--in your wristwatch!
71. 'Carbonado' is the name given to A) only the very best diamonds B) lumps of pure carbon
C) Spanish diamonds
D) diamonds made up of many small crystals
72. The art of cutting and polishing precious stones remained crude until A) the fourteenth century
B) the fifteenth century
C) the sixteenth century
D) the seventeenth century
73. During faceting, diamonds are held in copper holders
A) to facilitate accurate cutting
B) to make them shine more brilliantly
C) so that they can revolve more easily
D) as a steel holder might damage the diamond
74. The value order of `water' in diamond, _
A) is more important than their colour
B) ranges from blue-white upwards
C) ranges from blue-white downwards
D) has never been reliably established
75. Industrial diamonds are used
A) for a wide range of purposes
B) mainly for dentists' drills
C) for decoration in rings and watches
D) principally in mass-produced jewellery
Passage Two
Just about everyone knows the meaning of `value" though you'd never know it from the excesses of the Eighties. Clever campaigns often allowed marketers to charge more for their product and reap ever-higher profits. It worked like a dream until suddenly, facing difficult economic times, consumers work up.
Now, to the extent that they're buying, many consumers are choosing the car that delivers the most for the money--not necessarily the one they coveted as a status symbol a few years ago, they are shifting to the toothpaste that works from the ones with it slickest promotions. Companies that understand this new consumer have come up wit something new: "value marketing".
A word of caution is necessary. In marketing, watchwords quickly metamorphos into buzzwords--and value is no exception. We're not taping about ads that merely boast of a product's value or even such legitimate sates tools as price cuts and discount: Used correctly, value marketing amounts to much more than just stashing prices distributing coupons. It means giving the customer an improved product, with adds, features and enhancing the role of marketing itself:
In value marketing, marketing becomes part of the system for delivering value t( the consumer. Instead of merely shaping image, such a program might offer enhance guarantees or longer warranties, ads that educate rather than hype, membership club: that build loyalty, frequent-buyer plans, improved communications with customer. through 800 numbers, or package design that makes the product easier to use or more environmentally friendly.
上一页 [1] [2] [3] [4] [5] [6] [7] [8] 下一页
责任编辑:小草