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An early example is the 3rd-century CE Greek Pseudo-Callisthenes Romance of Alexander that says Alexander the Great once speared a fish, "in whose bowels was found a white stone so brilliant that everyone believed it was a lamp. Alexander set it in gold, and used it as a lamp at night" (Laufer 1915: 58).
The round brilliant cut is preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly-shaped crystals such as macles are more likely to be cut in a fancy cut —that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
This is a partial list of the largest non-synthetic diamonds with a rough stone (uncut) weight of over 200 carats (40 grams). [1] The list is not intended to be complete—e.g., the Cullinan (formerly Premier) mine alone has produced 135 diamonds larger than 200 carats since mining commenced.
The diamond cut planning stage is a complex process that requires the cutter to work with unique rough stones. Very often, the location of the inclusions in a rough stone will determine the type of shape to which a diamond may be cut. For economic reasons, most diamonds are cut to retain weight instead of maximizing brilliance. [2]
The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to per carat value. For instance, a 2.20-carat (440 mg) octahedron may produce (i) either two half-carat (100 mg) diamonds whose combined value may be higher than that of (ii) a 0.80-carat (160 mg) diamond plus a 0.30-carat (60 ...
Cutting and polishing diamonds in the Netherlands 1946. The art of cutting a gem is an exacting procedure performed on a faceting machine.The ideal product of facet cutting is a gemstone that displays a pleasing balance of internal reflections of light known as brilliance, strong and colorful dispersion which is commonly referred to as "fire", and brightly colored flashes of reflected light ...
A ratio of 1.33 to 1.66 provides a good traditional range of oval-shaped diamonds. Pear-shaped diamonds are also known as the teardrop shape owing to their resemblance and is considered as a hybrid between the marquise cut and the round brilliant diamond. The stone has one end rounded while the other end is pointed.
Eilat stone; Epidosite; Glimmerite; Goldstone (glittering glass) Tiger's eye; Helenite (artificial glass made from volcanic ash) Iddingsite; Kimberlite; Lamproite; Lapis lazuli; Libyan desert glass; Llanite; Maw sit sit; Moldavite; Obsidian; Apache tears; Pallasite; Peridotite (also known as olivinite) Siilinjärvi carbonatite; Soapstone (also ...