Sometimes we have an Agate, sometimes we have a Jasper, sometimes we have a name and not sure which exact gemstone we have. Many times we try to find an "easy answer" where there isn't one. 
The basic difference between Agate and Jasper is a structural one - at the microscopic level. It has nothing to do with the color or pattern. Agate is composed of microscopic 'fibers' of crystalline quartz. Jasper is composed of microscopic 'grains' of crystalline quartz. Jasper has less-regular patterns and is less defined than the Agates. Another subtle difference between the two is that Agates tend to be translucent (or at least contain translucent bands), while Jaspers are generally opaque.
The basic difference between Agate and Jasper is a structural one - at the microscopic level. It has nothing to do with the color or pattern. Agate is composed of microscopic 'fibers' of crystalline quartz. Jasper is composed of microscopic 'grains' of crystalline quartz. Jasper has less-regular patterns and is less defined than the Agates. Another subtle difference between the two is that Agates tend to be translucent (or at least contain translucent bands), while Jaspers are generally opaque..
This is a warm and comfortable design that incorporates Autumn colors - orange brown, red and rust. By using a colorful Agate/Jasper pendant, Breciated Jasper carved twists, Carnelian rounds and Antique Brass beads with crystal highlights, we make a smooth transition from the warmth of Summer to the coolness of Autumn. Matching French Hook earrings complete the set.
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Agate - No gemstone is more creatively striped by nature than agate. This distinct and dramatically banded variety of Quartz comes in layers. Agate composition varies greatly and can be of many colors. Each individual Agate forms by filling a cavity in a host rock. As a result, Agate often is found as a round nodule with concentric bands like the rings of a tree trunk. It is said to be named for the place it first was found along the River Achates (now called the River Drillo) in Sicily. .
Jasper coming from Greek origin, "iaspis", means "spotted stone." This form of semiprecious microcrystalline Quartz is usually red, brown or green. Its patterns are much less regular and defined than those of its sister variety, Agate. Although the term Jasper is often applied to unidentified stones, true Jaspers are metamorphic rocks. Jasper derives its colorful patterns from other minerals present, and is often named according to its pattern. It has a dull luster but takes a fine polish, and its hardness and other physical properties are those of Quartz. Jasper is often sealed with petroleum products. Its polish might wash away in water, so clean with a soft, dry cloth. .
Carnelian is an A-grade Agate. What a lot of people call "true carnelian" is the fiery red/orange color, and in theory, Carnelian is naturally that color. However, most of that fiery red/orange "true" Carnelian is heat-treated in secret before it reaches the gemstone-cutting factory. 
This apparently has been a secret for thousands of years; each part of the world thought everyone else's Carnelian was naturally red, but they were heating theirs, too. When held against the light, the color-treated Carnelian shows its color in stripes, while natural Carnelian shows a cloudy distribution of color. The name Carnelian is said to be derived from the Latin word 'carnis' ("flesh") due to its color. Deposits of Carnelian are found in Brazil, India, Australia, Russia, Madagascar, South Africa, Uruguay and the U.S.A. .
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