Because they're rare. Nothing else.
No. Pink diamonds are little more but they are both more expensive then colorless diamonds.
Sometimes. Diamonds can come in a variety of different colour. Pink diamonds are actually among the world's rarest and most expensive diamonds.
Blue diamonds are extremely rare, more rare than even pink diamonds. As with anything that is rare and well coveted its definitely going to be more expensive.
Generally pink diamonds are found in Australia. Australia's Argyle mine, in far north Western Australia, produces around 90% of the world's supply of pink diamonds. These are the world's only "intense" pink diamonds. Pink diamonds, one of the most rare and expensive diamonds in the world, are also mined in India, Brazil and Africa, but these are lighter in colour.
Pink diamonds are the rarest and the most expensive of diamonds in the market. Prices can run into the millions due to their rarity. An affordable alternative is pink sapphires which many jewelers recommend.
Black diamonds are more porous and from younger sedimentary rocks, so they are not as expensive as other diamonds.
Diamonds are not sold by centimeters, but by caret, color, quality. Pink diamonds have a tendency to be expensive. I suggest a pawn shop might give you a good value.
Given the same carat weight, clarity and cut, you will pay more for a pink diamond than for a 'white' or colourless diamond.
Any pink diamond is known as a pink diamond, and its description may include 'fancy', 'intense', 'light' and so forth. Pink diamonds can also be described as pink-purple, and more. You can follow the link below and find three important pink diamonds in the list.
Natural pink diamonds are more rare than natural yellow diamonds, probably because the common trace element nitrogen is responsible for a yellow cast in a diamond. Some colourless or 'white' diamonds are considered yellow, when graded with a colour grade from I to Z, as below. Natural pink diamonds exist 'due to structural anomalies" according to Wikipedia, and are very rare. Some diamonds can be altered (or enhanced) to appear yellow or pink, and when altered, are less valuable than naturally colored diamonds.
'Expensive' diamonds are only available in about 20% of all diamonds mined, the remainder being industrial diamonds. Of that 20%, only a few stones are large enough, clear enough, colorful enough or flawless enough to be sold as 'expensive' diamonds.
Black diamonds that are available in the market are usually low grade white diamonds that have been colored black, however, natural black diamonds can be expensive depending on the quality.