AeroGel, It cost About $300 billion per milligram.
Just a comment here: That is debatable. The very chemical composition of AeroGel makes it about 99% air. That means its actual mass at that weight (1 milligram) is considerable. If you are going for "most expensive material on earth" by actual amount/size/mass, it's probably antimatter. Again, debatable. Oh, almost forgot: the last time I did any research on this, antimatter (especially antiatoms like antihydrogen), were at $1,750 trillion US Dollars (USD) per ounce.
Diamonds
The most expensive diamond, by definition, is priceless.
The most expensive company in the world is, Saudi Aramco. Revenues over 240 Billion a year.
Oxygen is the most abundant element on the Earth's surface (or "crust"). It comprises 49.5 percent of the total mass (amount) of the Earth's crust, waters, and atmosphere. Silicon is the second most abundant element. Silicon dioxide and silicates (salts derived from silicon dioxide) make up about 87 percent of the materials in the Earth's crust. (Source: Tzimopoulos, Nicholas D., et al. Modern Chemistry, pp. 289, 758.) However water is the most common substance on the surface of the Earth. In the atmosphere, Nitrogen is the most common element (78%). It is believed that the core of our planet is mostly made of iron (at very high pressure and density), so iron would be the most common element within the Earth.
yup
Diamonds
Silk or Cotton
I don't know about top 5 but the most expensive material to ever exist was anti-matter. It cost 62.5 TRILLION dollars per gram.
the most expensive material used to make a casket, bronze, is considered by the industry to be the material most suitable for casket construction due to its strength and natural ability to resist rust
Rock is the most abundant material in the crust.
The Iron at the Earth's core is magnetic and is the most abundant, at the earth's crust, Lodestone is the most abundant naturally occurring magnetic material.
The iPhone 4
Depends on what type of material it is, where you buy it and if its cheap or not.
No,the second most abundant
dark green emeral is the most expensive thing on earth and olso i have some dark green emerald
Yes it is.
Very simple, because the material is more expensive. http://www.seatcoverset.com/seatcovers-car_seat_cover.htm