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Synthetic sapphire and spinel are durable materials (hardness 9 and 8) that take a good polish; however, due to their much lower RI when compared to diamond (1.762–1.770 for sapphire, 1.727 for spinel), they are "lifeless" when cut. (Synthetic sapphire is also anisotropic, making it even easier to spot.)
As of 2020, the most expensive non-synthetic element by both mass and volume is rhodium. It is followed by caesium, iridium and palladium by mass and iridium, gold and platinum by volume. Carbon in the form of diamond can be more expensive than rhodium. Per-kilogram prices of some synthetic radioisotopes range to trillions of dollars.
Around 2016, the price of synthetic diamond gemstones (e.g., 1-carat stones) began dropping "precipitously", by roughly 30% in one year, becoming clearly lower than that of mined diamond gems. [120] As of 2017, synthetic diamonds sold as jewelry were typically selling for 15–20% less than natural equivalents; the relative price was expected ...
There are considerable price shifts near the edges of the size bands, so a 0.49 carats (98 mg) stone may list at $5,500 per carat = $2,695, while a 0.50 carats (100 mg) stone of similar quality lists at $7,500 per carat = $3,750. Stones near the top of a size band (or rarer fancy coloured varieties) tend to be uprated slightly.
Polyhedral representation of spinel MgAl 2 O 4. Spinel (/ s p ɪ ˈ n ɛ l, ˈ s p ɪ n əl / [7]) is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl 2 O 4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals. [5]
Tanzanite is the blue and violet variety of the mineral zoisite (a calcium aluminium hydroxyl sorosilicate), caused by small amounts of vanadium. [3] Tanzanite belongs to the epidote mineral group.
The value of a diamond gemstone depends upon colour and quality, as well as weight. As of April 2024 the average price per carat of diamonds of between 1.00 and 1.49 carats was US$4,448. [49] The price of diamonds dropped significantly from a peak in 2022; prices of natural gems in shops dropped by 26% by the beginning of 2025.
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 ...