A unit employed in weighing diamonds, pearls, and other gemstones, which formerly ranged from 185.5 to 205.3 milligrams. Now the International metric carat is equal to 0.2 gram, or 200 milligrams and this is the standard in a majority of countries. Abbrev
An unfaceted, highly polished, cut gemstone, in which the top of the gem forms a dome-shaped or curved, convex surface. The base may be flat, convex or concave. The girdle outline may be round, oval, square, triangular, polygonal, or any other fancy shape
A gemstone that has been associated, by superstitions and religious tradition as appropriate to the time or month of one's birth. There are also birthstones for days, hours, signs of the zodiac, and seasons. Also called natal-stone.
A transparent to semitransparent, cyclo-silicate mineral species. Varieties of beryl are emerald, aquamarine, heliodor or golden beryl, bixbite, goshenite, maxixe, and morganite. Rare spelling: berylline. Sometimes showing chatoyancy and exhibiting star e
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
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.
American Gemological Laboratories is a unit of Collectors Universe, the leading provider of value-added authentication and grading services for high-value collectibles and gemstones, which was founded in 1986 and publicly traded since 1999. In 1977, Ameri
Founded in 1981, the American Gem Trade Association is a group of US and Canadian professionals dedicated to promoting the natural colored gemstone and cultured pearl trade while maintaining the highest ethical standards among its members and within the i
An artificial gem comprised of lithium aluminum silicate and made in a variety of colors. Neodymium as a coloring agents yields pink lavender colors. A vivid, laser blue variety blue is colored by copper.
Alexandrite of Brésilia aproximatively 14 carats with another one half smaller of same crystal !!! at Alexandrite discussion forums | Alexandrite guide
Alexandrite gemstone buyer and jewelry collector guide is a comprehensive encyclopedia with articles, guides, glossary and bibliography covering all the major branches of alexandrite gemstone and jewelry knowledge.
Alexandrite gemstone buyer and jewelry collector guide holds information on history, lore, value and properties of the chrysoberyl varieties, including alexandrite and cymophane gemstones.