Because they are a very rare mineral. Because they sparkle when cut and worn as jewellery. Because they are so hard that they are used in machine tools for the purpose of cutting other hard substances.

The value of diamonds has nothing to do with how rare it is. A international Corp -De Beers- holds a monopoly on diamonds and controls the release into the market place. They determine the value by controlling supply. They always make sure that there is more demand for the stones than supply, to maintain top prices. De Beers is now banned from trading in the US because for unfair business practices. There logo was "A diamond is forever"

Basically its because of supply and demand!

Because of the expertise that it takes to cut and polish them,and because people are prepared to buy them at any price.

It is simple stone!!!!!!!!!!! Mining(Excavating), Cutting, polishing will make it expensive.

because its quite a process to get it from within the earth unto your finger, on your ear and around you arm/neck. because they are a girl's best friend;) because our materialist society esteem the possesion thereof so highly they are forever... they just plain simple gorgeous...:)

I think because people die trying to find them and because they last forever :)

They are a rarity.

Thanks Mr.LiAr, Diamonds Are expansive because of its clarity, carat, cut and color of the diamond.Also they expansive because they are best for the one you loves.

"Historically, the wholesale diamond price has been controlled by De Beers Group, which has an estimated 40% to 50% of the market. Botswana is currently the largest producer of diamonds with mines operated by Debswana, a joint venture between De Beers and the Botswana government. However, since the 1980s, other producers have developed new mines in Russia, Canada and Australia for example, challenging De Beers' dominance (historically De Beers market share was considerably higher, e.g. 80%). De Beers through its trading company known as the DTC raised wholesale diamond prices three times in 2004 by a total of 14%. The United States is the biggest consumer of diamonds in the world. The U.S. accounts for 35% of diamond sales, Hong Kong 26%, Belgium 15% (Antwerp is the world's diamond-trading centre), Japan 6%, and Israel 4% . Israel and Belgium are important Hubs for trading diamonds thus consumption numbers are a bit misleading. The price of diamonds fluctuates with global demand and the world economy. Diamond prices vary widely depending on a diamond's carat, color, clarity and cut (The 4 C's). In contrast to precious metals, there is no universal world price per gram for diamonds. However the industry does use tools such as the Rapaport Diamond Report and The Gem Guide which are published weekly or quarterly, as a price references." Source and further information: http://en.wikipedia.org/wiki/Diamonds_as_an_investment Further information: - "The Price of Diamonds - Why Are They So Expensive?" http://www.wyrdology.com/stones/natural/diamond-cost.html - "Some Of The Reasons Why Diamonds Are So Expensive": http://ezinearticles.com/?Some-Of-The-Reasons-Why-Diamonds-Are-So-Expensive&id=335881 http://www.streetdirectory.com/travel_guide/35069/jewelry/som_of_the_reasons_why_diamonds_are_so_expensive.html http://www.albaspectrum.com/Jewelry2/32.htm

Because there are fools stupid enough to pay big money they can't afford to have a piece of social status. The market determines the price. If people decided one day they didn't like them any more they fall to about the price of cubic zirconium.

The price of diamonds are kept at a high price as those mining them (De Beers and the likes) keep a tight grip on the amount of supply that actually goes out. I've heard of them torching large stockpiles of their own diamonds to keep them from reaching the market and lowering the price of them. Diamonds aren't rare as you can find them around any place that had carbon deposits (graphite, for example) deep in the ground that a hot spot or other volcanic activity brought magma in very close proximity to it. It just so happens the deposits in Africa are easy to mine thanks to uplift and erosion bringing them up to the surface. Also, there was a large advertising campaign starting around the 1920-1930s launched by De Beers that pitched diamond rings as signs of everlasting love and made them the cultural norm for marriage proposals. Other then that, diamonds really don't have any practical use that cheaper, and stronger, artificial ones don't do better. All giving a diamond ring to your loved one says is that many dark-colored people in a far off land living in perpetual squalor toiled away to pluck this rock from the depths of the earth under the rule of a brutal international conglomerate. And you approve of all of this. It's humorous that there is now a distinction between "blood" diamonds and "legit" diamonds. The only difference being the "legit" diamonds were mined by modern-day slaves of a company with enough money to pay off the oversight personnel. It's a terrible industry. Don't buy natural diamonds. Send a message.

rare = expensive with any item Since the mining of diamonds can be controlled, so can the price.