Gold emerald in the world of colored gemstones

Gold emeralds are a status esteem in the world of colored gems, but little is known about the low-key "nobles." There are very few opportunities that ordinary people can see with their own eyes. However, because it has the advantages of all high-grade gemstones, and the color is very special, it is more and more popular, and hope to know more about this gem.

The main component of gold emerald is alumina crucible, which refers to a variety that does not have discoloration or cat's eye effect. The crystal form is often short columnar, plate-like, transparent to opaque, glass to eucalyptus luster, and the color depends on the amount of iron contained therein. Light yellow, yellow, green, yellow, yellow, green, yellow and brown. The dichroism is obvious, the hardness is 8.5, the density is 3.73 g/cm3, and the toughness is excellent. There are three famous variants of the gold emerald: Alexandria or the stone, the cat's eye and the stone cat's eye.

First, the origin and variety

The main producing areas of gold emeralds are Sri Lanka, Russia, Brazil, Myanmar, Madagascar, the United States, Tanzania, Zimbabwe and other countries.

Gold emerald cat's eye is a gold emerald with cat's eye effect. It is rich in color, such as honey yellow, yellow green, brown green, yellow brown, brown and so on. Among all the gemstones, there are many varieties of gemstones with cat's eye effect, but only the gold emerald cat's eye can really be called "cat's eye". The tubular inclusions distributed in parallel in the gemstone crystal can be concentrated and reflected by the curved gemstones, and a light band like a cat's eye is displayed. When the cat's eye gemstone is rotated, the light band is opened. It is like a cat's eyes, so it gets its name. Since the best cat eyes are produced in Sri Lanka, the old name is “Ceylon Cat Eye”.

Cats are mainly produced in Sri Lanka, Brazil, Madagascar, Myanmar, India, and Russia. The gold-orange gemstone eyeliner is thin and bright, which is the best cat-eye effect in all gemstones. The higher the content of fine, dense and parallel filament rutile or tubular inclusions in the crystal, the more obvious the cat's eye effect. Conversely, the cat's eye effect is less obvious. Under the concentrating light source, the cat's eye gemstone presents half of the light to its body color, while the other half is milky white; the general color of the cat's eye gemstone is honey color, and the color of "white honey yellow" appears in the light.

The stone is a chrome-plated gold emerald, a variant of the gold emerald, and enjoys the reputation of "the emerald in the day, the ruby ​​in the night". The transparent crystal of the stone can only pass red light and green light. In the daytime light source, there are many green components, and it is green. In the evening light source, there are many red components, and it is red.

There are few places where the stone is changed. In addition to Russia, Brazil, Myanmar, Zimbabwe and Zambia have also discovered. Among them, the best marble is produced in the Ural region of Russia.

The stone cat eye refers to a gold emerald that has both a color changing effect and a cat eye effect. It is an extremely rare rare treasure. Not only does it have a clear to strong discoloration effect, but it also has a pronounced cat-eye effect. The only place where the cat's eye is changed is Sri Lanka. Its products are rare in both domestic and foreign markets, so the value is extremely high.

Second, the processing techniques of cat eyes

The processing of gold emeralds is based on the principle of maximizing the effect of discoloration and minimizing defects. The transparent crown is round and multi-faceted, the pavilion is stepped, and the style is the most common. The cat-eye effect is processed into a curved surface. The medium-high convex shape and the double convex shape are the most common, mainly to increase the weight of the stone. . In addition, in order to make the light belt more clear and flexible, the top generally has a high protrusion and the bottom is usually not polished.

Because the stone has a strong pleochroism and the pleochroism changes to green-light yellow-red, the orientation of the stone must be red or green from the mesa direction, even if the table is perpendicular to one of the colors. The ground shows the discoloration effect of the stone. The orientation of the cat's eye gem is such that the bottom surface of the gemstone is parallel to the C axis of the crystal. If it is elliptical, the long axis of the ellipse should be perpendicular to the C axis.

Third, the identification of similar gemstones and imitations

There are many kinds of cat's eye effects in gemstones, but they are not as precious as gold-green cat eyes. Commonly used as a gemstone or imitation of cat's eye: Lezi stone, also known as quartz cat's eye, is very similar to cat's eye gemstone, but its hardness is low, the same size is not as heavy as cat's eye gemstone, and the light is weak and not clear; wood becomes stone, and It is called the tiger eye stone, which has obvious linear reflection, but its texture is rough, the light is vague and the flexibility is poor. When the artificial cat eye rotates, the curved top can see two or three bright bands, the light is dull, the beauty is not enough, and the natural The cat's eye has only one bright band.

There are several kinds of spinel, garnet and sapphire similar to nature in nature. Andalusite is similar to marble because of its strong yellow-green and red dichroism, but the reddish color appears under the same light source, and the refractive index is lower. The refractive index of andalusite is 1.63 to 1.65, and the density is 3.12? 3.18 g / cm 3, both much lower than the stone. The difference between the stone and the spinel and the garnet is that the latter two are not polarized and pleochroic, and the stone changes in different directions, the different directions of the stone can also be different under the same light source. colour. The difference between a stone and a color sapphire is that the color change effect is different, and the refractive index is also significantly different. Sapphire is blue-violet during the day and red at night, and the lowest refractive index is greater than the highest value of the stone.

Fourth, the purchase standard

Gold emeralds are rarely seen in jewelry stores, and their value is related to weight, color, transparency, and cut. The larger the gemstone particles, the brighter the color, and the higher the transparency, the higher the value. Among them, the high-transparency green, golden yellow, and sunflower yellow gold emeralds have the highest price, and the golden brown emerald has a lower brown value. Diamond emeralds with a diameter of more than 3 mm and often honed are often collected by collectors.

The first condition of the high-grade gold-green cat's eye is that the eye line is centered, straight, bright and complete. The most expensive color is honey yellow or sunflower yellow, honey yellow is especially good, and the rest are dark yellow, yellow green, dark green, brown. Green, yellowish brown, brown, etc. Generally, the larger the particle size of the golden-green cat's eye, the higher its collection value. In terms of clarity, it is better to have less cracks and cracks, but as long as the crack or flaw is not in a conspicuous position, the grade of the gemstone is not greatly affected.

The factors affecting the price of the stone are mainly the color-changing effect, size, transparency and enthalpy of the stone. Generally speaking, the stone with large grain size, high transparency and little reduction has a high price. The more obvious the color change effect, the higher the price.