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Known to the ancient Greeks as ἀδάμας (adámas, 'proper, unalterable, unbreakable') [3] and sometimes called adamant, diamond is the hardest known naturally occurring material, and serves as the definition of 10 on the Mohs scale of mineral hardness. Diamond is extremely strong owing to its crystal structure, known as diamond cubic, in ...
Diamond certified FL (flawless) by the GIA Two diamonds of grade VS 1 and SI 2 respectively. The GIA diamond grading scale is divided into six categories and eleven grades. [2] The clarity categories and grades are: [3] Flawless category (FL) diamonds have no inclusions or blemishes visible under 10× magnification. [3]
Gold-filled material is made by bonding a layer of gold alloy to a base metal core (typically brass, but sometimes copper or silver). This creates a material with the appearance and durability of solid gold, but at a lower cost. Gold-filled material is used to create a variety of products, including: Jewelry: Gold-filled is a popular choice for ...
There are several scales of durometer, used for materials with different properties. The two most common scales, using slightly different measurement systems, are the ASTM D2240 type A and type D scales. The A scale is for softer ones, while the D scale is for harder ones. The image of Bareiss digital durometer is shown in the photo.
Diamonds with higher color grades are rarer, in higher demand, and therefore more expensive, than lower color grades. Oddly enough, diamonds graded Z are also rare, and the bright yellow color is also highly valued. Diamonds graded D–F are considered "colorless", G–J are considered "near-colorless", K–M are "slightly colored".
The superficial Rockwell scales use lower loads and shallower impressions on brittle and very thin materials. The 45N scale employs a 45-kgf load on a diamond cone-shaped Brale indenter, and can be used on dense ceramics. The 15T scale employs a 15-kgf load on a 1 ⁄ 16-inch-diameter (1.588 mm) hardened steel ball, and can be used on sheet metal.
Carob seeds have been used throughout history to measure jewelry, because it was believed that there was little variance in their mass distribution. [10] However, this was a factual inaccuracy, as their mass varies about as much as seeds of other species. [11] In the past, each country had its own carat. It was often used for weighing gold.
The price was $6m above the $15m pre-sale estimate and more than three times the price of $6.5m it reached when it was last sold in 1993. The price fetched was a world record for a Golconda diamond and a world record price per carat for a colorless diamond. [1] [2] [3] [4]
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