These metals have not been found as sources of color in natural aquamarine. However, richly colored synthetic aquamarine has been produced using cobalt, copper, and nickel as sources of color. Some synthetic aquamarine receives its color from iron, like natural aquamarine. Synthetic aquamarine (lab-grown aquamarine) has been produced by hydrothermal growth methods in Russia since at least the 1980s and since the early 2000s in the Czech Republic. These tests can also be used to separate synthetic maxixe (also known an maxixe-type beryl) from synthetic aquamarine. Maxixe can be separated from aquamarine in the following ways:ġ) by its pleochroism (the strongest pleochroic color of maxixe is seen when the maxixe crystal is viewed down its c-axis, but in aquamarine the strongest blue color is seen when viewing the crystal perpendicular to the c-axis),Ģ) by its response under an ultraviolet lamp (some maxixe will glow a greenish color under both short- and long-wave ultraviolet radiation), and,ģ) a lack of iron in its chemical composition (The iron content test will not be reliable for specimens of synthetic aquamarine which have received their blue color from cobalt or another chromophore.) If Maxixe loses its color, it can be irradiated in a laboratory, however, the renewed blue color will also fade. Unfortunately, the blue color gradually fades to a pale brownish color upon exposure to light. The blue color develops while the gem material is still within the Earth by exposure to natural radiation. Maxixe (pronounced "mashish") is a rare variety of beryl with a dark blue color. This information is important to many buyers - even to buyers of low-cost items. The color improvements achieved by heat treatment are thought to be permanent and undetectable by current methods of testing.Īny time a gem has been heated, irradiated, dyed, or undergone other treatments to improve its color, durability or appearance, the seller should disclose that information to the buyer. Most of the aquamarine offered for sale in today's market has received heat treatment. Greenish yellow and other colors of beryl can be altered to colors within the aquamarine range by heat treatment. Gentle heat treatment can remove the yellow color and transform the gem's color to a more pure and more valuable blue. Most natural aquamarine has a greenish blue color. Ferrous iron (Fe 2+) is responsible for blue color, and ferric iron (Fe 3+) is responsible for yellow color (which combines with the blue color to produce greenish blue). The iron can occur in two oxidation states. The greenish blue to blue color of aquamarine is caused by trace amounts of iron.
Aquamarine Color and TreatmentĪs a member of the beryl mineral family, aquamarine has a chemical composition of Be 3Al 2Si 6O 18. Heat-Treated Aquamarine: The blue color of this 0.52-carat faceted aquamarine from Madagascar was improved by heat treatment. It can be difficult to find a small gem with a rich blue color, but as the size of the stone increases, the opportunity to find strong color also increases. As the size of the gem increases, the strength of its apparent color will also increase. Size: Aquamarine is available in a wide range of sizes. A small aquamarine with a rich blue color will cost a lot more than identical-size stones with a faint blue color. Gems with a rich blue color are much more expensive because rich color in aquamarine is very rare.
Gems with a faint blue color are abundant and inexpensive.
.jpg "aquamarine beads")
A mounting that guards the stone from impact and not wearing the gem during activities that might result in accidental impact are important precautions.Ĭolor: The price of aquamarine is mainly determined by weight and the strength of its color. However, aquamarine's tenacity is rated as brittle - which means that the gem can be easily chipped upon impact. Hardness is a property that enables a gem to resist scratching. Diamond, ruby, sapphire, topaz, and chrysoberyl are the only popular gemstones that are significantly harder. If you are interested in purchasing an item of aquamarine jewelry, here are a few things to consider:ĭurability: Aquamarine has a Mohs hardness of 7.5 to 8, making it one of the harder gemstones. Hexagonal (often occurs in prismatic to tabular crystals with a hexagonal cross section)Īquamarine has a hardness and durability that makes it suitable for all jewelry uses.Īquamarine is such a popular gemstone that it can be found in almost any jewelry store in the United States. Hardness and relatively low specific gravity. Greenish blue to blue (color almost always has been improved by heat treatment)Ĭrystals are prismatic, often with flat terminations, hexagonal, and without striations.
0 kommentar(er)
