If yes, is cloud-milk the brand
name of the diamond or is it just
describing the color or what?
You'll see that the following descibes
diamonds as being shaped like milk cartons
Diamond
Diamond is a transparent crystalline form of carbon, and is the hardest substance found in nature. (A new substance was synthesized in 1957: borazon, which is as hard as
diamond and will scratch it.)
Diamond is a poor conductor of heat and electricity; it is 3.5 times as dense as water. The
diamond crystal structure was one of the first to he determined by X-RAY diffraction. Each carbon atom was found to be surrounded tetrahedrally (in a four sided figure) by four other carbon atoms, and this structure spreads throughout the whole CRYSTAL. So each crystal is a giant molecule.
Diamonds that are used in jewellery can occasionally be coloured by traces of impurities. Many
diamonds are imperfect and these crystals are used industrially. Their extreme hardness gives them ideal qualities for use in drilling, cutting and grinding.
Diamonds are found mainly in South Africa and Brazil. Because
diamond is denser than graphite it is theoretically possible to convert graphite to
diamond. It was only in the 1950s that the right heat and pressure conditions for conversion were found. Up to now only small (0.1 carat) high quality industrial
diamonds have been made, none of gem standard. It is also interesting, if the heats of combustion of
diamond and graphite are compared, that graphite is thermodynamically the more stable allotrope.
Diamond can be made to burn in air if heated to between 600° and 800°C.
Pure carbon has two allotropes, or different solid forms:
diamond and graphite.
[Note - Recently the allotrope c60 has been found to be a solid form of Carbon]
The difference is caused by the way the atoms are arranged.
Diamond (left) has atoms that form a stack of tetrahedrons figures with four triangular sides- a shape seen in some milk cartons. This arrangement is reflected in the shape of a complete
diamond crystal. Graphite (above) is composed of flat planes of hexagonal rings of atoms; the planes can slide over each other, so graphite is slippery.
Diamond color
Jewelers set
diamonds in groups of similar colors.A chemically pure and structurally perfect
diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural
diamonds are absolutely perfect. The color of a
diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. For example, most white
diamonds are discounted in price when more yellow hue is detectable, while intense pink or blue
diamonds (such as the Hope
Diamond) can be dramatically more valuable. Out of all colored
diamonds, red
diamonds are the rarest of all.
Possible colors
The Hope DiamondDiamonds occur in a restricted variety of colors — steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Colored
diamonds contain interstitial impurities or structural defects that cause the coloration, whilst pure
diamonds (which are exceedingly rare) are perfectly transparent and colorless.
Diamonds are scientifically classed into two main types and several subtypes, according to the nature of impurities present and how these impurities affect light absorption:
Type I
diamond has nitrogen (N) atoms as the main impurity, commonly at a concentration of 0.1 percent. If the N atoms are in pairs they do not affect the diamond's color; these are Type IaA. If the N atoms are in large even-numbered aggregates they impart a yellow to brown tint (Type IaB). About 98 percent of gem
diamonds are type Ia, and most of these are a mixture of IaA and IaB material: these
diamonds belong to the Cape series, named after the diamond-rich region formerly known as Cape Province in South Africa, whose deposits are largely Type Ia. If the N atoms are dispersed throughout the crystal in isolated sites (not paired or grouped), they give the stone an intense yellow or occasionally brown tint (Type Ib); the rare canary
diamonds belong to this type, which represents only 0.1 percent of known natural
diamonds. Synthetic
diamond containing nitrogen is Type Ib. Type I
diamonds absorb in both the infrared and ultraviolet region, from 320 nm. They also have a characteristic fluorescence and visible absorption spectrum (see Optical properties of
diamond).
Type II
diamonds have very few if any nitrogen impurities. Type IIa
diamond can be colored pink, red, or brown due to structural anomalies arising through plastic deformation during crystal growth—these
diamonds are rare (1.8 percent of gem
diamonds), but constitute a large percentage of Australian production. Type IIb
diamonds, which account for 0.1 percent of gem
diamonds, are usually a steely blue or grey due to scattered boron within the crystal matrix; these
diamonds are also semiconductors, unlike other
diamond types (see Electrical properties of
diamond). However, an overabundance of hydrogen can also impart a blue color; these are not necessarily Type IIb. Type II
diamonds absorb in a different region of the infrared, and transmit in the ultraviolet below 225 nm, unlike Type I
diamonds. They also have differing fluorescence characteristics, but no discernable visible absorption spectrum.
Color intensity scale
The Gemological Institute of America (GIA) uses a "D" to "Z" scale it developed for grading the color of "white" (non-fancy colored)
diamonds, where "D" is colorless and "Z" is yellow:
colorless: D, E, F
near colorless: G, H, I, J
faint yellow or brown: K, L, M
very light yellow or brown: N, O, P, Q, R
light yellow or brown: S, T, U, V, W, X, Y, Z
Other
diamond grading agencies, notably the European Gemological Laboratory (EGL) and the American Gemological Society (AGS), also use the color scale developed by the GIA.
Diamonds that rate toward the colorless end of the range are sometimes known as "high-color"
diamonds, and those toward the other end, "low-color"
diamonds. These terms refer to the relative desirability (as demonstrated by market prices) of color grades, not the intensity of the color itself.
Diamond color is graded by comparing a sample stone to a master set of
diamonds with colors defined as "D" through "Z".
Diamonds having a color more intense than "Z" are considered fancy colored
diamonds, and can be graded using separate systems which indicate the characteristics of the color, and not just its presence. These color grading systems are more similar to those used for other colored gemstones, such as ruby, sapphire, or emerald, than they are to the system used for white
diamonds.
There is no scientific standard for grading the color
diamonds. While the GIA may grade a diamond's color an "I", the EGL may grade the same
diamond a "H", and a jeweler who has not had the
diamond certified may claim it to be a "G".
Value of colored
diamonds
Diamonds that enter the Gemological Institute of America's scale are valued according to their clarity. For example, an "E" rated
diamond (colorless) is much more valuable than a "Y" rated
diamond (light yellow or brown). This is due to two effects: high-color
diamonds are rarer, limiting supply; and the bright white appearance of high-color
diamonds is more desired by consumers, increasing demand. Poor color is usually not enough to eliminate the use of
diamond as a gemstone: if other gemological characteristics of a stone are good, a low-color
diamond can remain more valuable as a gem
diamond than an industrial-use
diamond.
Diamonds that go out of scale in the rating are known as "fancy color"
diamonds. These
diamonds are valued using different criteria than those used for regular
diamonds. When the color is rare, the more intensely colored a
diamond is, the more valuable it becomes.
Fancy-colored diamonds such as the deep blue Hope Diamond are among the most valuable and sought-after
diamonds in the world.
Advertisement 
0 
In 
