HERE ARE MORE THAN 58 FACTS ABOUT ONE OF THE MOST EXPENSIVE PRESENTS YOU'LL EVER RECEIVE

1 . Diamonds are the hardest substance known to man.

2 . They are pure carbon that crystallised many millions of years ago.

3 . Every diamond in the world is unique. No two are the same.

4 . Diamonds are weighed in carats - the word comes from the seeds of the 'carob' tree which because they have a uniform weight, ancient gem dealer used as weights for their scales.

5 . A single diamond weighing 2 carats is worth more than twice as much as two one carat stones of the same quality.

6 . Only a diamond can cut another diamond.

7 . The best colour for a diamond is no colour - the cool white of an icicle or a gin and tonic. The rarest stones are pure white, called 'exceptional white'.

8 . The best way to see a rough diamond's true colour is to view it against a white background.

9 . Rough gem-quality diamonds are sorted into more than 5,000 categories and sold at diamond 'sights' in London ten times a year.

10 . A rough diamond looks like a dull glass pebble.

11 . Most polished diamonds have 58 facets to bring out their maximum sparkle, fire and brilliance.

12 . These facets are ground on to the diamond one by one.

13 . The simplest way to clean a diamond is in a bowl of warm water to which a mild soap has been added.

14 . Diamonds can scratch each other. So don't jumble them together in a box.

15 . The atmosphere of Venus was first analysed through the diamond window of a U.S. spacecraft. Only diamond has the strength and transparency to cope.

16 . Until the 15th century, only kings wore diamonds, as a symbol of strength courage and invincibility.

17. In the 15th century, when Archduke Maximilian of Austria gave a diamond engagement ring to Princess Mary of Burgundy, women began to wear diamonds.

18. A Diamond of over one carat in weight is one in a million

19. A well cut diamond will reflect the majority of light within the diamond before reflecting it back out of the top giving the stone its brilliance and fire.

20. Diamonds have a grain like wood, along which cleaving is possible.

21. Diamonds can be sawn by a thin disc coated with oil and diamond dust.

22. But some diamonds can be 'cleaved' by hand with a blade. It has to be done with great skill or thousands of pounds can be lost.

23. A diamond will melt at 6,900 degrees F. This is 2 1/2 times greater than the melting point of steel.

24. Diamonds are very good conductors of heat (four times better than copper) which is why they are so cold to touch.

25. They are poor conductors of electricity.

26. Diamonds were first found in India more than 2,500 years ago. For centuries that was the only source.

27. Then, in the 18th century, they were discovered in Brazil.

28. The first diamond in South Africa was discovered near to what is now known as Kimberley in 1866.

29. Diamonds are still mined there. The diamonds are found in kimberlite which forms a volcanic 'pipe'.

30. In Namibia, diamonds are found on the Atlantic beaches. They have been washed down by rivers to the sea.

31. On average, 200 tons of kimberlite have to be mined to produce a one carat polished diamond.

32. Only 20% of the world's rough diamond production can be considered to be of gem quality.

33. The rest are used for industrial purposes - cutting, grinding, drilling or polishing

34. The largest diamond ever discovered was the Cullinan. It originally weighed just under 121 pounds.

35. The Cullinan was cut into 9 major stones, 2 of which are in the Crown Jewels, and 96 smaller ones.

36. All the rough gem quality diamonds found in the world in one year could be carried by a 2.5 ton truck.

37. Other diamond producing countries include Australia, Angola, Botswana, Brazil, Central African Republic, China, Ghana , Guinea , India , Ivory Coast , Liberia, Russia, Sierra Leone, Tanzania, Venezuela and Zaire.

38. A carat is one fifth of a gram. Each carat is divided into 100 points. A point is about the weight of three breadcrumbs.

39. The word 'diamond' comes from the Greek 'adamas' meaning unconquerable.

40. 'A diamond is forever' is understood and accepted by women throughout the world.

41. 'Fire' is the blaze of rainbow colours into which a diamond breaks up the white light that is reflected out of it.

42. 'Scintillation' is the flash of light that occurs when a diamond is moved, even fleetingly.

43. The simpler and thinner the setting of a ring, the better it will show off the full beauty of the diamond.

44. The early Egyptians believed the 'vena amoris' (the vein of love) ran directly from the heart to the top of the third finger, left hand. Hence, rings are often worn in this way.

45. Generally speaking, the larger the diamond, the rarer it is.

46. Diamonds are 140 times harder than rubies or sapphires. And 180 times harder than emeralds.

47. The Koh-i-noor (Mountain of Light) is the worlds most famous diamond. Weighing 108.93 carats and oval, it was first mentioned in 1304. It is now among the Crown Jewels.

48. Cupid's arrows were said to be tipped with diamonds.

49. The blue Hope diamond (44.5 carats) is supposed to be unlucky for its owners. It is held responsible for the deaths of Marie Antoinette and Louis XIV. Henry Philip . Hope bought it in London in 1830. All his family died in poverty. It is now in the Smithsonian Institute in Washington.

50. Most diamonds have natural inclusions, however infinitesimally small. The fewer the inclusions, the better the diamond's clarity.

51. There are amber, blue, brown, cinnamon, champagne, green, pink and yellow diamonds. These rare coloured diamonds are known as 'fancies' .

52. Zsa Zsa Gabor once said 'I never hated a man enough to give him his diamonds back' .

53. Cutting and polishing normally reduces the weight of a rough diamond by more than 50%.

54. The most popular diamond shape is the round brilliant. But you can get pear, oval, marquise, heart, emerald, square and baguette cuts.

55. Legend has it there is an inaccessible valley, situated on the Khorasian border in Central Asia which is carpeted with diamonds. It is said to be 'patrolled by birds of prey in the air, and guarded by snakes of murderous gaze on the ground' .

56. 100 years ago, diamonds were often mounted in silver. Today, gold and platinum (hard yet malleable) are the perfect complement .

57. 'Diamonds are a Girl's Best Friend' was the title song in the musical 'Gentlemen Prefer Blondes' .

58. Four characteristics affect a diamond's value - cut, clarity colour and carat weight - the 4 Cs.

59. The Greeks believed the fire in a diamond reflected the constant flame of love - nothing has changed.