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Bauhin observed that when water was poured into the cup with the wood shavings, the water shortly turned into "a wonderful blue and yellow color, and when held up against the light beautifully resembled the varying color of the opal, giving forth reflections, as in that gem, of fiery yellow, bright red, glowing purple, and sea green most ...
Chiapan amber has a number of unique qualities, including much that is clear all the way through and some with fossilized insects and plants. Most Chiapan amber is worked into jewelry including pendants, rings and necklaces. Colors vary from white to yellow/orange to a deep red, but there are also green and pink tones as well.
Stones that show a dramatic color change and strong colors (e.g., red-to-green) are rare and sought-after, [8] but stones that show less distinct colors (e.g. yellowish green changing to brownish yellow) may also be considered "alexandrite" by gem labs such as the Gemological Institute of America. [13] [14]
The intense blue color is due to the presence of the trisulfur radical anion (S •− 3) in the crystal. [16] The presence of disulfur (S •− 2) and tetrasulfur (S •− 4) radicals can shift the color towards yellow or red, respectively. [17] These radical anions substitute for the chloride anions within the sodalite structure. [18] The S ...
The word prasiolite literally means "scallion green-colored stone" and is derived from Greek πράσον prason meaning "leek" and λίθος lithos meaning "stone". The mineral was given its name due to its green-colored appearance. Natural prasiolite is a very light, translucent green. Darker green quartz is generally the result of ...
Some tourmaline gems, especially pink to red colored stones, are altered by heat treatment to improve their color. Overly dark red stones can be lightened by careful heat treatment. The pink color in manganese-containing near-colorless to pale pink stones can be greatly increased by irradiation with gamma-rays or electron beams.
Peridot is one of the few gemstones that occur in only one color: an olive-green. The intensity and tint of the green, however, depends on the percentage of iron in the crystal structure, so the color of individual peridot gems can vary from yellow, to olive, to brownish-green. In rare cases, peridot may have a medium-dark toned, pure green ...
The "classic" bloodstone is translucent to opaque green chalcedony and red jasper that contains inclusions of hematite. The red jasper may resemble spots of blood , hence the name bloodstone . Other colors of chalcedony may also occur in Indian bloodstone, such as white, yellow, or blue.