alexandrite natural of photo stone

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301. Ultramafic: A type of igneous rock characterized by a high content of mafic minerals, particularly olivine, pyroxenes, amphiboles, etc. The silica content is less than 45%.; HTML, 23 Kb, 2008-07-20 13:07:15; /chapters/glossary/ultramafic.html
302. Ultrasonic cleaning: A device for cleaning dirt and other foreign particles from gemstones and jewelry articles by subjecting them to ultrasonic vibrations immersed in water or other solvent. The articles must be free of stress flaws. Glass lenses and other bodies can be poli; HTML, 24 Kb, 2008-07-20 13:07:17; /chapters/glossary/ultrasonic-cleaning.html
303. Ultraviolet lamp: A mercury discharched lamp in quartz glass designed to produce ultraviolet light for exciting luminescence in gem minerals specially diamonds. The long-wave lamp is provided with wood's glass filter to emit wavelengths between 400 nm and 300 nm. To obtain; HTML, 24 Kb, 2008-07-20 13:07:20; /chapters/glossary/ultraviolet-lamp.html
304. Ultraviolet microscope: A special magnifying device for investigating the objects are illuminated by ultraviolet light in the range 180 to 400 nm. The resolving power is increased corresponding to the resolution of shorter wavelengths than visible light. It requires special quar; HTML, 24 Kb, 2008-07-20 13:07:22; /chapters/glossary/ultraviolet-microscope.html
305. Vacuum fluorescence display: A miniature cathode ray tube (CRT), which is closet to cover glass and heated cathode made of tungsten wire emits electrons. The electrons are accelerated by positively charged by hexagonal steel and passing through the grid to anodes covered with blue fl; HTML, 24 Kb, 2008-07-20 13:07:26; /chapters/glossary/vacuum-fluorescence-display.html
306. Vanadium: A very hard, light-gray, ductile, malleable, metallic element of the group V of the Periodic System with the symbol V. It is one of the 8 pigment metals responsible for color in gemstones such as beryl, sapphire (natural or synthetic). Used as a component; HTML, 24 Kb, 2008-07-20 13:07:28; /chapters/glossary/vanadium.html
307. Volcanic glass: A solid volcanic natural form of glass (rock) produced by sudden cooling and solidification of viscous lava before crystallization can take place, such as obsidian, pitchstone or other glassy masses. Obsidian is used for tumbled gems, ornamental objects,; HTML, 24 Kb, 2008-07-20 13:07:30; /chapters/glossary/volcanic-glass.html
308. Volcanic rock: Generally a fine crystalline or glassy igneous rock, which is formed by the solidification of molten magma or lava on the Earth's surface during volcanic action. Such as basalt, obsidian, etc.; HTML, 24 Kb, 2008-07-20 13:07:32; /chapters/glossary/volcanic-rock.html
309. Water of crystallization: Water molecules, which have been chemically combined in certain crystals or hydrated salts, which are given off when the crystals are heated.; HTML, 23 Kb, 2008-07-20 13:07:37; /chapters/glossary/water-of-crystallization.html
310. Wave form of light: The pictorial graphical representation of the shape of a wave obtained by plotting the values of the periodic quantity against the time.; HTML, 23 Kb, 2008-07-20 13:07:39; /chapters/glossary/wave-form-of-light.html
311. Wavelength: The distance between two points having the same phase on the following or preceding wave. The wavelength of electromagnetic radiation is equal to the velocity of the wave divided by its frequency =c/v. It is measured in nanometers unit.; HTML, 24 Kb, 2008-07-20 13:07:41; /chapters/glossary/wavelength.html
312. Weathering: A natural geological description for disintegration and decomposition of rocks and minerals as consequent exposure to atmospheric agents at or near the Earth's surface such as chemical action of air, rainwater, frost, insolation, bacteria, plants, and mec; HTML, 24 Kb, 2008-07-20 13:07:43; /chapters/glossary/weathering.html
313. Weight of gemstones and precious metals: A standard mass. The unit of weight of gemstones since 1913, is the international metric carat or decimally of them in points.; HTML, 23 Kb, 2008-07-20 13:07:44; /chapters/glossary/weight-of-gemstones-and-precious-metals.html
314. X-ray: The produced wavelengths of X-rays according to the electromagnetic theory of light consisting of continuous band of wavelengths, which are a mixture of all wavelengths. Depends on the used voltage of apparatus, which is know as white X-ray radiation or g; HTML, 24 Kb, 2008-07-20 13:07:48; /chapters/glossary/x-ray.html
315. X-ray crystal spectrometer: A device to obtain an X-ray spectrum for determining the wavelength of its chemical consistent. Each element, when irradiated by electrons, emits X-ray of several characteristic frequencies the line spectrum depending on the atomic number.; HTML, 24 Kb, 2008-07-20 13:07:50; /chapters/glossary/x-ray-crystal-spectrometer.html
316. X-ray filters: To generate monochromatic X-rays or line spectrums only one wavelength used is a suitable selective filter made of very thin layers of metal elements. There have one or two atomic numbers lower than the target metal such as nickel with atomic number 28 us; HTML, 24 Kb, 2008-07-20 13:07:52; /chapters/glossary/x-ray-filters.html
317. X-ray fluorescence: If a crystal is irradiated by an intense X-ray or gamma-ray beam, this includes the substance to emit its visible characteristic secondary X-ray line spectra of a longer wavelength, which is known as X-ray fluorescence. It is a nondestructive method. Used; HTML, 24 Kb, 2008-07-20 13:07:53; /chapters/glossary/x-ray-fluorescence.html
318. X-ray spectrum: Several characteristic lines of the spectrum of X-ray, which are emitted by a bombardment of material with electrons such as curved dark lines on the films produced by X-ray method of powder diffraction of stone or minerals.; HTML, 24 Kb, 2008-07-20 13:07:55; /chapters/glossary/x-ray-spectrum.html
319. Y-axis: One of the 3 optic axes and intermediate axis in biaxial crystal.; HTML, 23 Kb, 2008-07-20 13:07:59; /chapters/glossary/y-axis.html
320. Yehuda treatment: A colorless glass-like material used as an impregnation or filling agent to improve the appearance and reduce the visibility of inclusions in stones such as diamonds and emeralds.; HTML, 24 Kb, 2008-07-20 13:08:01; /chapters/glossary/yehuda-treatment.html
321. Yellow chrysoberyl: Yellow greenish to light yellow or brown chrysoberyl, which contains ferric iron as an impurity. Has an absorption spectrum band at first part of the violet at 444 nm, which can be seen in some chrysoberyl cat's-eye.; HTML, 24 Kb, 2008-07-20 13:08:02; /chapters/glossary/yellow-chrysoberyl.html
322. Young-Helmholtz theory of color vision: The theory that the eye contains three different groups of retinal fibers (cones) with maximum response to three primary colors to red-yellow, green, and blue violet, which are parts of the spectrum.; HTML, 24 Kb, 2008-07-20 13:08:04; /chapters/glossary/young-helmholtz-theory-of-color-vision.html
323. Yttrium: A dark gray, silvery luster, rare earth metallic element of the Periodic System with the symbol Y. Flammable when powder from. Used in alloys and as a metal deoxidizer.; HTML, 23 Kb, 2008-07-20 13:08:06; /chapters/glossary/yttrium.html
324. Zonary growth: Zonary growing of crystals bounded by plane crystal faces, which occur by slight variation in the composition of a crystal due to separation or interruptions of the crystal phases during growth.; HTML, 24 Kb, 2008-07-20 13:08:10; /chapters/glossary/zonary-growth.html
325. Zone: A group of crystal faced intersection, which are parallel to a common line.; HTML, 23 Kb, 2008-07-20 13:08:12; /chapters/glossary/zone.html
326. Zone axis: A line runs through the center of a crystal, to which all faces of a given zone are parallel.; HTML, 23 Kb, 2008-07-20 13:08:13; /chapters/glossary/zone-axis.html
327. Zone of crystal faces: In crystallography a characteristic feature of a serie faces of a crystal where those intersection lines with each other are all parallel.; HTML, 23 Kb, 2008-07-20 13:08:16; /chapters/glossary/zone-of-crystal-faces.html
328. Zoning: The straight, parallel growth-lines in the internal structure of a gemstone with definite angles, usually seen in some stones, which occur by slightly variation in the chemical composition within the crystal due to separation or interruptions of the cryst; HTML, 24 Kb, 2008-07-20 13:08:17; /chapters/glossary/zoning.html
329. A Bibliography of Alexandrite Gemstone Buyer and Collector's Guide: An annotated bibliography of Alexandrite Gemstone Buyer and Collector's Guide; HTML, 59 Kb, 2008-07-20 13:08:19; /chapters/bibliography.html
330. Is there a difference between Russian and Brazilian Alexandrite gemstones?: The mining of alexandrite in Russia lasted less than 100 years from the time it was discovered in 1833 to the early 1900’s. It was George Kunz, the gemologist/gemstone buyer for Tiffany & Co that probably did the most to popularize this unique gemst; HTML, 27 Kb, 2008-07-29 08:09:57; /chapters/faq/is-there-a-difference-between-russian-and-brazilian-alexandrite-gemstones.html
331. What makes natural alexandrite so expensive?: Alexandrite is an expensive gemstone because it so rare and production has always been limited. For years, the only source for alexandrite was Russia. In the last 20 or 30 years several new discoveries of alexandrite have been reported but production of s; HTML, 25 Kb, 2008-07-29 08:10:06; /chapters/faq/what-makes-natural-alexandrite-so-expensive.html
332. What is the difference between chrysoberyl and alexandrite?: Chrysoberyl is the species name and Alexandrite is the variety name. Alexandrite is that variety of chrysoberyl that changes color as a function of the light source; green in daylight and red under incandescent light.; HTML, 25 Kb, 2008-07-29 08:10:13; /chapters/faq/what-is-the-difference-between-chrysoberyl-and-alexandrite.html
333. What is the difference between cat's eye and alexandrite?: Cat's eye is the popular name for an optical effect known as chatoyancy in the gemological nomenclature. Microscopic needle-like inclusions inside the stone reflect a streak of light that appears to open and close as the stone is rotated -- hence the eye; HTML, 26 Kb, 2008-07-29 08:10:22; /chapters/faq/what-is-the-difference-between-cat-s-eye-and-alexandrite.html
334. What causes the cat's-eye effect in chrysoberyl?: The cat's-eye effect is caused by the reflection of light off of minute, parallel, needle-like rutile crystals or hollow tubes within the stone. Cat's eye inclusions are aligned parallel to the crystallographic axis and the stones are always cut as caboch; HTML, 25 Kb, 2008-07-29 08:10:30; /chapters/faq/what-causes-the-cat-s-eye-effect-in-chrysoberyl.html
335. Are there any other gemstones which change color?: Several other well known gemstones, including diaspore, sapphire, garnet and spinel may also change color as a function of the light source but the color change of top alexandrites is distinctive and attractive under any light conditions.; HTML, 26 Kb, 2008-07-29 08:10:37; /chapters/faq/are-there-any-other-gemstones-which-change-color.html
336. Why does alexandrite appear to change color in sunlight and artificial light?: Alexandrite is a trichroic gemstone which absorbs and reflects light differently in each of its three optical directions. Spectroscopic analysis reveals a different absorption spectrum for each of the three optical directions. The differences in absorptio; HTML, 26 Kb, 2008-07-29 08:10:46; /chapters/faq/why-does-alexandrite-appear-to-change-color-in-sunlight-and-artificial-light.html
337. What are the most common colors of alexandrite?: Unfortunately, most alexandrites show either a nice color in daylight or an attractive color under incandescent light. Rarely are both colors bright and vivid and often stones that change to bright red under incandescent light are only brown or almost bla; HTML, 26 Kb, 2008-07-29 08:10:53; /chapters/faq/what-are-the-most-common-colors-of-alexandrite.html
338. How much will a typical one carat alexandrite gemstone cost?: The retail replacement cost for a 1ct. alexandrite could be anywhere between $500 to $12,000 per carat. The intensity of the color change and the attractiveness of the colors are the most important factors in determining the value of an alexandrite. With; HTML, 25 Kb, 2008-07-29 08:11:03; /chapters/faq/how-much-will-a-typical-one-carat-alexandrite-gemstone-cost.html
339. Is alexandrite the most expensive gemstone in the world?: Along with diamonds, rubies, and emeralds, top quality alexandrites are among the most expensive gemstones in the world. In larger sizes over 4.00 or 5.00cts., Burmese rubies are more rare and expensive than alexandrites but in sizes below 1.00cts., alexa; HTML, 26 Kb, 2008-07-29 08:11:10; /chapters/faq/is-alexandrite-the-most-expensive-gemstone-in-the-world.html
340. Why is natural alexandrite better than synthetic alexandrite?: Natural alexandrite is not better than synthetic alexandrite but natural alexandrite is very rare and uncommon in modern jewelry because it is hardly ever available and because it is too expensive for the general public to buy. Even lower quality more inc; HTML, 26 Kb, 2008-07-29 08:11:15; /chapters/faq/why-is-natural-alexandrite-better-than-synthetic-alexandrite.html
341. Are there any ways to improve alexandrite colors by any special treatment like heating?: Alexandrite cannot be improved by any kind of thermal treatment. Although some have tried, heat treatment does not seem to affect alexandrite at all. Some lower quality cracked alexandrites are oiled to hide the cracks but beyond that, alexandrite is not; HTML, 24 Kb, 2008-07-29 08:11:21; /chapters/faq/are-there-any-ways-to-improve-alexandrite-colors-by-any-special-treatment-like-heating.html
342. How can I spot the difference between a natural and a synthetic alexandrite?: HTML, 26 Kb, 2008-07-29 08:11:26; /chapters/faq/how-can-i-spot-the-difference-between-a-natural-and-a-synthetic-alexandrite.html
343. I have an alexandrite ring that my parents purchased in the 50s, what are the chances the stone is a genuine natural alexandrite?: It is very unlikely that even an old alexandrite ring could contain a natural alexandrite. Natural alexandrites, especially large clean stones are extremely rare and almost never available at any price. Most old inherited alexandrite rings are actually sy; HTML, 27 Kb, 2008-07-29 08:11:37; /chapters/faq/what-are-the-chances-an-alexandrite-purchased-in-the-50s-is-natural.html
344. Where do the best alexandrite gemstones come from?: Although Russian alexandrites have the most historical value, fine stones are occasionally available from deposits in Brazil, India, Tanzania, Madagascar, and Sri Lanka. Unfortunately, there has been little production of alexandrites from any deposit in r; HTML, 26 Kb, 2008-07-29 08:11:44; /chapters/faq/where-do-the-best-alexandrite-gemstones-come-from.html
345. What is the best way to clean and take care of alexandrites?: With a hardness of 8.5, Alexandrite is a tough, hard, and durable gemstone that doesn't require any special attention. Still, even the hardest gemstones can shatter with a single well-placed blow so caution is always a good idea. Washing dishes with your; HTML, 25 Kb, 2008-07-29 08:11:53; /chapters/faq/what-is-the-best-way-to-clean-and-take-care-of-alexandrites.html
346. Where can I buy natural alexandrite gemstones?: Fine alexandrites or alexandrite jewelry can be purchased from jewelers specializing in colored gemstones, at trade shows, from TV sellers, at high end jewelry auctions, or online from websites specialized in alexandrite. You would be unlikely to find a h; HTML, 25 Kb, 2008-07-29 08:12:01; /chapters/faq/where-can-i-buy-natural-alexandrite-gemstones.html
347. Is the June birthstone pearl or alexandrite?: Various birthstone lists have been used in different cultures for thousands of years.; HTML, 25 Kb, 2008-07-29 08:12:12; /chapters/faq/is-the-june-birthstone-pearl-or-alexandrite.html
348. Where can I test and appraise my alexandrite?: The most well known gemological laboratories are listed below and all of them are equipped to test alexandrite. Most gemological laboratories only identify gemstones, they do not appraise them.; HTML, 28 Kb, 2008-07-29 08:12:19; /chapters/faq/where-can-i-test-and-appraise-my-alexandrite.html
349. What do I need to check before purchasing alexandrite gemstone?: First and foremost, we need to look at the quality and strength of the color change. A strong change where the colors are bright and attractive under any kind of light is most desirable. Many stones are either a beautiful green in daylight or a nice pinki; HTML, 26 Kb, 2008-07-29 08:12:28; /chapters/faq/what-do-i-need-to-check-before-purchasing-alexandrite-gemstone.html
350. How can I check the color change in an alexandrite: Two kinds of light are required to observe color change; daylight and incandescent light?; HTML, 25 Kb, 2008-07-29 08:12:38; /chapters/faq/how-can-i-check-the-color-change-in-an-alexandrite.html
351. Alexandrite World Occurrences and Mining Localities: Directory of confirmed findings and current mining localities of alexandrite, cat´s eye and chrysoberyl gemstones; HTML, 34 Kb, 2008-07-31 07:32:37; /localities/index.html
352. Australian alexandrite, Dowerin: Information about Australian alexandrite findings and mining in Dowerin, Australia.; HTML, 30 Kb, 2008-07-31 07:32:43; /localities/alexandrite-locality-australia-western-australia-dowerin.html
353. Brazilian alexandrite, Carnaiba Mine: Information about Brazilian alexandrite findings and mining in Pindobacu, Brazil; HTML, 30 Kb, 2008-07-31 07:32:55; /localities/alexandrite-locality-brazil-bahia-curaca-river-valley-caraiba-mine.html
354. Brazilian alexandrite, Caraiba mine: Information about Brazilian alexandrite findings and mining in Pindobacu, Brazil.; HTML, 30 Kb, 2008-07-31 07:33:05; /localities/alexandrite-locality-brazil-bahia-pindobacu-carnaiba-mine.html
355. Brazilian alexandrite, Serra Dourada: Information about Brazilian alexandrite findings and mining in Serra Dourada, Brazil.; HTML, 32 Kb, 2008-07-31 07:33:18; /localities/alexandrite-locality-brazil-goias-minacu-serra-dourada.html
356. Brazilian alexandrite, Esmeraldas de Ferros: Information about Brazilian alexandrite findings and mining in Esmeraldas de Ferros, Brazil.; HTML, 29 Kb, 2008-07-31 07:33:30; /localities/alexandrite-locality-brazil-minas-gerais-ferros-esmeraldas-de-ferros.html
357. Brazilian alexandrite, Novo Cruzeiro: Information about Brazilian alexandite findings and mining in Novo Cruzeiro, Brazil.; HTML, 29 Kb, 2008-07-31 07:33:39; /localities/alexandrite-locality-brazil-minas-gerais-aracuai-novo-cruzeiro.html
358. Brazilian alexandrite, Hematita: Information about Brazilian alexandrite findings and mining in Hematita, Brazil.; HTML, 29 Kb, 2008-07-31 07:33:47; /localities/alexandrite-locality-brazil-minas-gerais-hematita.html
359. Brazilian alexandrite, Itaitinga Mine: Information about Brazilian alexandrite findings and mining in Itabira, Brazil.; HTML, 29 Kb, 2008-07-31 07:33:56; /localities/alexandrite-locality-brazil-minas-gerais-itabira-itaitinga-mine.html
360. Brazilian alexandrite, Teafilo Otoni: Information about Brazilian alexandrite findings and mining in Novo Cruzeiro, Brazil.; HTML, 30 Kb, 2008-07-31 07:34:05; /localities/alexandrite-locality-brazil-minas-gerais-teofilo-otoni.html

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Alexandrite

alexandrite natural of photo stone

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