Posts Tagged ‘precious stone’
Andalusite
Posted on: October 5, 2011
Andalusite
Andalusite is best known for its strong pleochroism and its unusual color which is frequently a mixture of both red and green. It is not a color changing gem. It often shows two colors, (red and green) at the same time. Rough crystals will often show green in one direction and red in another. The color is difficult to match on any standard color chart.
Sourses: Andalusite is an attractive and unusual gemstone, first discovered in Andalusia,Southern Spain, after which it is named. It has some similarities with the more expensive alexandrite, as both are strongly pleochroic. It is suitable for use in jewellery as it is quite hard. The fact that it is seldom seen in jewelry is probably because it is quite rare, and most people, even in the jewellery industry, have never heard of it, let alone seen it. Gem quality Andalusite is found inAustralia,Brazil,Russia,Spain,Sri Lanka(Ceylon) and theUnited States. In addition to this, there are some Andalusite deposits in theUnited Kingdom, although the crystals found there are not of gem quality.
Evaluation :
Andalusite is rated at 6.5 – 7.5 on the Moh’s Scale of Hardness, making it a durable gemstone, suitable for every day wear.
Andalusite is found in brown, brownish-green, gray, green, greenish-brown and red. Andalusite gemstones display pleochrism, meaning that a single stone displays different colorations, depending on the angle the stone is viewed at. In addition to this, one variety of Andalusite commonly displays a cross (crucifix), which is present due to natural inclusions. This variety of Andalusite (Chiastolite), is often set in a pendant and is particularly sought after in staunchly Catholic countries due to the symbolism of the cross.
Common Cuts :
The color displayed by an Andalusite stone is often dictated by the way it is cut. Andalusite is commonly cut into Emerald, Marquise, Oval, Round and Square shapes. Emerald, Marquise and Oval cuts tend to make the stone display one central color, with a differing color at each end, whereas Round and Square Cuts commonly create a mosaic effect, blending different colors together beautifully.
Routine Enhancements :
Whilst Andalusite can be heat-treated in order to improve color, this is rarely needed.
Luster is vitreous
Cleavage is good in two directions.
Fracture is splintery to subconchoidal.
Other Characteristics: dark inclusions produce cruciform shapes in the variety chiastolite. Index of refraction is 1.632-1.638.
Color
Andalusite is a gem that is capable of displaying different colors at the same time. This is different from the color changing gems like Alexandrite and the color changing garnets, because the different colors on Andalusite are displayed at the same time. This is called pleochroism, which is caused by the double refraction of light in a stone. When the two rays of light pass through the stone, they travel at both different angles & speeds, and display different colors of the spectrum. This allows a person to see different colors on the stone, when viewed from different angles, in the same light source. For the color changing stones like Alexandrite and color change garnets, it is necessary to have two different light sources to be able to see the color change.
Typical colors for andalusite are green, brown, red, greenish-brown, brownish-green. Its pleochroic colors are red, green and yellow.
Because of the pleochroism, the color of an andalusite can be affected considerably by the direction in which it is cut.
Our photograph is disappointing and deceptive. The actual stone is a pleasant greenish brown to red. We used flash lighting with a digital camera, followed by software adjustment of the lighting levels, and the effect was to make the stone appear quite a dull brownish color.
Star Andalusite or Chiastolite
An impure variety of andalusite known as chiastolite contains carbonaceous inclusions in a cruciform arrangement. These are cut as cabochons and polished for use as amulets in many countries, largely because of the symbolism of the cross.
Ametrine
Posted on: October 5, 2011
Ametrine is a Silicon Dioxide and is a member of the Quartz family. The unusual color variation in Ametrine is due to the presence of iron impurities in different oxidation states within the crystal structure
History:
The name Ametrine was coined for a member of the Quartz family which displays a combination of both Amethyst and Citrine.
Natural Ametrine first arrived in the market in 1980 when it was discovered at the Anhai mine inBolivia. This mine became well- known when a Spanish conquistador received it as a dowry when he married a princess from the Ayoreos tribe in the seventeenth century.
Ametrine is said to aid meditation, to calm and relieve tension, and dispel negativity . It is also believed to have all the metaphysical properties of both Amethyst and Citrine:
Amethyst has been thought to protect against intoxication and to help maintain a sober and serious mind. Amethyst opens and activates the crown chakra, the third eye chakra, and can also open the heart chakra. Amethyst can be used to fight a number of disorders including headaches, insomnia, hearing disorders, heart disorders, digestive system disorders, and has even been thought to help stabilize mental disorders. Amethyst also works emotionally and spiritually by providing patience, balance, calmness, and peace
It has been said that Citrine helps to manifest your goals and keeps the wearer cheerful. In ancient times, Citrine was carried as protection against snake venom and evil / impure thoughts. Citrine does not absorb negative energies but rather dissipates and transmutes them, which is why this stone is good for clearing your aura. It attracts abundance, prosperity, and success, and because of this Citrine has been nicknamed the “success stone.” Citrine stimulates the solar plexas and third eye chakras, promoting stamina and activating intuition. It can also help to overcome sleep related problems such as insomnia and nightmares. Physically it is said to help with poor blood circulation, digestion, allergies, and an aid to curing life-threatening diseases.
Sourses:
Until very recently, the world’s only source of this bicolored natural quartz is the Anahi Mine located in the jungles ofBolivia. It is rumoured that the mines where first discovered by native Indians in the seventeenth century. The Bolivian government declared the land a state reserve and built a fortress near the mine entrance. Despite its remote location, ametrine (as well as natural amethyst and citrine) made its way across the border toBrazil. These goods were then sold as Brazilian products. This caused a change in the government inBoliviain 1989. The rights to the mine were sold, and during the past decade, these collectible gems became available on the domestic marketplace.
*Miners in the Brazilian state ofBahiaare finding small amounts of this combination amethyst/citrine.
Ametrine is among an elite group of gems, because as of now there is just one source of this treasure in the world. You should add an ametrine to your collection now, since its future availability is uncertain at best.
Medicine: Ametrine is very helpful in getting rid of depression. This leads to inner peace and tranquility.
Many believe that it contains the powers of amethyst and citrine in one stone, making it a very powerful money stone as well as an excellent via to higher psychic awareness and spiritual enlightenment.
Evaluation :
Ametrine is rated at 7 on Moh’s Scale of Hardness and is a durable gemstone that lacks cleavage. Ametrine combines the appeal of both the violet-purple Amethyst and the yellow-orange Citrine in one bi-colored gemstone. Ametrine gemstones can be found displaying an equal share of the Amethyst and Citrine as well as a blended color affect, displaying attractive shades of rosy gold and mauve. The most important aspects to consider when viewing an Ametrine is the depth and intensity of the colors and the distinctiveness of the separation. The creativity of the cut should also be taken into account.
Routine Enhancements :
Most of the Ametrine found on the market today is actually heat-treated Amethyst.
Availability :
Ametrine rarely occurs naturally and most of the Ametrine found on the market today is heat-treated Amethyst. For Ametrine to occur naturally, the iron impurities in the quartz have to be affected in different ways. For example, both sides of the stone must be subjected to two slightly different temperatures during the crystallization process of the Quartz for Ametrine to form. The only two known sources of natural Ametrine is the Anahi mine inBolivia and theRio Grande do Sul mine inBrazil. Although this gemstone is rare it is relatively inexpensive.
Cleaning :
Ametrine is best cleaned using warm soapy water and a soft brush. Though there is no special care required,
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