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Diamond is extremely strong owing to its crystal structure, known as diamond cubic, in which each carbon atom has four neighbors covalently bonded to it. Bulk cubic boron nitride (c-BN) is nearly as hard as diamond. Diamond reacts with some materials, such as steel, and c-BN wears less when cutting or abrading such material. [4]
Color grading of diamonds was performed as a step of sorting rough diamonds for sale by the London Diamond Syndicate. As the diamond trade developed, early diamond grades were introduced. Without any co-operative development, these early grading systems lacked standard nomenclature and consistency. Some early grading scales were; I, II, III; A, AA, AAA; A, B, C. Numerous terms
Diamond clarity is the quality of diamonds that relates to the existence and visual appearance of internal characteristics of a diamond called inclusions, and surface defects, called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat , color , and cut .
In 1953 the GIA developed its International Diamond Grading System and the "four Cs" (cut, clarity, color, and carat weight) as a standard to compare and evaluate the quality of diamonds. [ 2 ] As of 2024, the institute is headquartered in Carlsbad, California , and operates in 13 countries, with 11 campuses, 9 laboratories, and 4 research centers.
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 color appear to be of better grade than they actually are.
Yellow diamonds of high color saturation or a different color, such as pink or blue, are called fancy colored diamonds and fall under a different grading scale. [ 36 ] In 2008, the Wittelsbach Diamond , a 35.56-carat (7.112 g) blue diamond once belonging to the King of Spain, fetched over US$24 million at a Christie's auction. [ 60 ]
Its most important practical property is optical absorption, like in the color centers, which gives diamond green, or sometimes even green–blue color (in pure diamond). The characteristic feature of this absorption is a series of sharp lines called GR1-8, where GR1 line at 741 nm is the most prominent and important.
Discovered in 2015, it is the 5th largest diamond ever discovered at the Crater of Diamonds State Park, Arkansas Identified as a Type IIa crystal, the 8.52 carat diamond was cut and polished by Mike Botha into a custom-designed 4.605 carat Triolette shape during a week long event in North Little Rock and was graded a D IF, 0 Polish & 0 Symmetry ...