| | Diamond - Wikipedia, the free encyclopedia |
 | | Diamond is the hardest known natural material (second-hardest material to ultrahard fullerite), and is the most expensive of the two best known forms (or allotropes) of carbon, whose hardness and high dispersion of light make it useful for industrial applications and jewelry. |
 | | The luster of a diamond, its adamantine brilliance, is a consequence of refractive index of 2.417 (at 589.3 nm), which allows total internal reflection to occur easily. |
 | | The quality of a diamond's cut is widely considered the most important of the four Cs in determining the beauty of a diamond; indeed, it is commonly acknowledged that a well-cut diamond can appear to be of greater carat weight, and have clarity and colour appear to be of better grade than they actually are. |
| en.wikipedia.org /wiki/Diamond (9260 words) |