Amethyst Cabochons
Amethyst Cabochons Chrysoprase Gemstones Chrysoprase is considered the rarest and most valuable stone in the chalcedony quartz group. That's quite a distinction considering that the chalcedony spe...
Amethyst Cabochons
Chrysoprase GemstonesChrysoprase is considered the rarest and most valuable stone in the chalcedony quartz group. That's quite a distinction considering that the chalcedony species also includes agate, onyx, carnelian, bloodstone and jasper. But chrysoprase, it is fair to say, is also the least known of all the chalcedony varieties. The term chalcedony refers both to the bluish-white-gray variety in particular and to all the cryptocrystalline quartzes in general. The cryptocrystalline quartzes have microscopically small crystals and a waxy or dull luster in their natural state. The familiar macrocrystalline quartzes such as amethyst and citrine have much larger crystals which are recognizable with the naked eye, and have a vitreous luster. The name chrysoprase comes from the Greek for "gold-leek", though the name seems inappropriate today since chrysoprase is typically an apple-green. Chrysoprase is colored by traces of nickel and is in fact one of the few gemstones colored by nickel. Most green gemstones are colored by iron (such as peridot), chromium (emerald, chrome tourmaline, chrome diopside) or vanadium (tsavorite garnet). The color of chrysoprase can be quite vivid and is reminiscent of fine jade. The gemological references warn that the color can fade under prolonged exposure to sunlight or when heated, though the color may recover under moist storage. Chrysoprase has a hardness of 6.5 to 7 on the Mohs scale, and a density of 2.58-2.64. It has a refractive index of 1.530-1.540. It ranges from translucent to opaque. Chrysoprase has been used as a decorative stone since ancient times. A favorite of Frederick the Great of Prussia, chrysoprase can be seen decorating many buildings in Prague, including the Chapel of St Wenceslas. Today chrysoprase is carved or fashioned in cabochons or beads. It is also popular for intaglios and cameos. Like all forms of chalcedony, chrysoprase is durable enough for all kinds of jewelry applications, including rings. Chrysoprase is not known to be treated in any way, though dyed green agate is sometimes used as a simulant. Chrysoprase occurs in serpentine rocks and in weathered materials of nickel ore deposits. The most famous historical deposits were in Poland, but that mine has been worked out since the 14th century. Current sources include Australia, Brazil, India, Madagascar, Tanzania,Kazakhstan, Russia, Zimbabwe, South Africa, Tanzania and the USA (California). About the Author GemSelect is a leading online dealer in fine gemstones, including chrysoprase, sapphire, spinel, garnet, tourmaline and zircon. Chrysoprase Photos |
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Sapphires, rubies and emeralds: How are valued color gemstones
The colors of the rainbow caught forever in glittering jewels that take away breath. Color gemstones can rival diamonds for their beauty, but how do you value?
Even though sapphires, rubies and emeralds differ in color and weight, for example, there is a consistency in the way they are valued. And that includes lesser-known gems such as tourmaline, alexandrite, peridot, garnet and well. The four characteristics that determine the value in colored gemstones are color, clarity, cut and carat, but the most important is color, color and more color.
The intensity of color and the closer regard to the spectral color really means is more valuable the stone. Emeralds should be a pure green, red more red rubies and a deep blue sapphires. As the color varies from the ideal spectrum, the decrease in value. For example: Burmese rubies have the best color. The ruby are light red, red, orange, or with a touch of brown or a little blue are not as valuable.
The color is measured in intensity or saturation, ie color intensity. It also reflects the tone, or how close the color is close to pure spectral color, tone that is light or dark ie., How much is white or black in color, and finally the distribution of color or shape to the color on the other side and into the stone.
The other factors of clarity, cut and carats are not as important to the value of a stone that has the best color and conversely have a greater impact on the value of a stone is not as pure color.
Clarity is the absence of internal defects can be seen with a magnification of 10. Most natural colored gemstones with inclusions or defects. A good example is the emerald rarely are flawless. The lighter the color of the stone's flaws become more visible, while the darker the color of the stone the less obvious. Type fault and the location of the stone affects its value as well.
The cut is the way a stone is faceted to bring the best features of this particular stone for its type. The court emphasized color, fire and brilliance of the stone, without sacrificing one for another. Unlike diamonds, colored gemstones can also occur as an area known as smooth rounded cabochon cut. Cabochon cut sapphires and rubies often show a star and are known as star sapphires and star rubies.
Carat is the weight of the stone, not how big it is. The different types of gemstones have different weights when cut with the same size. Density Ruby is greater than the density of emeralds for a one carat ruby will be smaller than one carat emerald cut identically. The stones can be cut to look bigger too. Some gemstones are more readily available in heavy weights such as amethysts and tourmalines, emeralds say. For example: 18 carat tourmaline, have a lower value per carat of a 5 carat alexandrite by large tourmaline stones are more common than large stones alexandrite.
The highest safety precaution in the purchase of precious stones or precious gems is to buy from a jeweler you trust. You get what you pay for.
About the Author
Peace sign jewelry
celebrates the sixtieth anniversary of the peace sign. Dee Power is the author of several nonfiction books. Her hobbies include gardening, cooking and
fine jewelry
.