## Diamonds are a Girl’s Best Friend … When brains aren’t an option!!!!!

August 4, 2009

Girls.. you may think diamonds are your best friend, but not at the moment. According to this article from The Australian (27/7/09) sales for the world’s largest diamond-producer  are down by 57% at the moment. The price of diamonds should be dropping and indeed they are.

According to the most recent graphs I could find (below) from the Certified Diamond Exchange #mce_temp_url# diamond prices have dropped significantly from last year. And they are still dropping. Diamonds come in many sizes and shapes. So diamond graphs must compare similar diamonds eg. Large Fancy, Small round etc. The y-axis shows the price of the diamond compared to the Jan91 price which is set at 100.

Oooo!!! Aaaaeeee!!! Mathspigs Note: Cutting diamonds involves maths.. angles, symmetry, % and a lot of NERVE!!!

How big are BIG diamonds Or THAT ROCK YOUR WEARING EQUALS HOW MANY PAPERCLIPS?????

Let’s do some maths mathspigs!!!!!   Diamonds are measured in carats. 5 carats = 1 gram.  Now keep in mind that one paperclip weighs one gram. So we need some boxes of paper clips to do this exercise. Here are some examples of the largest diamonds in the world. More at: #mce_temp_url#  Convert these to grams and hence paper clips and feel  the weight. Would you want any of these diamonds hanging around your neck??????

The Blue Hope Diamond   is believed to carry a curse because two of the families who owned it died. It weighs 45.52 carats.

The Koh-I-Noor (Mountain of Light) weighs 186 carats and is a part of the crown jewels.

The Excelsior diamond originally weighed 995 carats but it was cut into 10 pieces. The largest diamond it produced was 158 carats.

The Taylor-Burton diamond weighs 240.8 carats.

The Cullinan I or Star of Africa Diamond is the world’s largest cut diamond weighing 530.20 carats. It is a part of King Edward VII’s Sceptre and is housed in the Tower of London which means Mathspig has seen it, sort of. To view the Crown Jewels in the Tower of London you must stand on a moving walk way that really whips along so you see a crown for about 3 seconds!!!!!!

Angles,  Symmetry and %’s.

As the school will not give you diamonds to cut – you could ask, but!!-  we will make  2-D images. We will do the top of the diamond looking down. (The images here show the top and the underneath projections.) Start with a circle, an oval (ellipse in maths) or a rectangle and see how you would make some cuts.  It is a good idea to locate the middle of your diamond. This will help with the symmetry. Then use a protractor to calculate the angles you used. This means you can do the same pattern again.

SUPER BLING CALCULATIONS FOR ADVANCED MATHSPIGS: Calculate the area in the middle of your diamond. This would be the part of the diamond you did not cut. The bigger this area the bigger the cut diamond will look and, of course, you are not wasting the gem by cutting it into little bits. Then calculate the total area of your shape. Now find the % of diamond left uncut. The bigger this % the better your gem cutting skills.