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Alexandrite: deposits, cut, certificate

Alexandrite: deposits, cut, certificate

June 24, 2021

Alexandrite origin

On the photo: a map of alexandrite deposits

Deposits

Natural alexandrite is mined and explored mainly in following countries: Tanzania, Brazil, India, Sri Lanka. From time to time mining activities are conducted in Russia, in Ural Mountings. But Uralian alexandrite samples are very difficult to find in the gemstone market. The Malysheva Mine is famous for its emeralds and alexandrites. Gem-quality alexandrites from Brazil and Tanzania usually display bluish-green in daylight and reddish-violet under incandescence light. Indian and Ceylon samples are often yellowish-green in daylight and orangish-red in yellow light. Samples from the Urals are famous for strong colorchange effect from green to raspberry red, such stones are highly valued in gemological world. It can be referred as brand, created by historical events, because this variety of chrysoberyl has been firstly found particulary in the Urals and it has good average gem-quality. Interesting, that record price per carat belongs to the Ural sample.

Cut

On the photo: an alexandrite with high-quality octagon-shaped cut under different lighting, 5.80 ct

Shape and quality of cutting are an important factor of evaluation. Oval shape is especially popular for natural alexandrite. You can see also alexandrites of another cut-forms on the gemstone market, of course. Proportions and angles of facets must be chosen correctly, such way as a stone looks bright, without a large window in the center, a «see-through» area without reflection. It happens, that Asian gem cutters try to save more weight in the finished stone during cutting, they make “deep” pavilions. Cabochons are made from opaque alexandrites or with a low degree of clarity. Symmetry, proper proportions and good polishing are important both for cut stones and cabochons.

“ Practical advice. Judge attractiveness of form and quality of cutting. Pay attention on symmetry of a stone, if it has «window», whether it influences on beauty or not. Is pavilion has right depth? Judge quality of polishing, are there any scratches or chips on the surface of facets. Many not very serious surface defects could be easily eliminated by recutting, which is usually quite inexpensive.“

Alexandrite cuts

Certificate on alexandrite

If you have any doubts about natural origin of alexandrite, then it makes sense to request from the seller or to order yourself a gem report from a well-known gemological laboratory. Careful comprehensive studies of inclusions, characteristics, chemical composition of a stone sometimes make it possible to determine even country of origin, which may be written in a document. Usually alexandrite isn’t an object of enhancement. Only in rare cases cracky stones could be improved by oiling in order to hide the cracks. The fact of alexandrite treatment is also reported in the certificate. At the present time, a synthetic analogue is produced by various methods. Some synthetic alexandrites can be very similar to natural ones not only in color, but also in inclusions. Also synthetic garnet and sometimes sapphires with the color change effect may look like natural alexandrite. You need to be sure that a stone is natural. For expensive samples the presence of a certificate from a reputable laboratory is highly desirable. Following laboratories are considered to has high reputation: GIA, SSEF, Gubelin GemLab, AGL, GRS.

In the photo: GRS certificate on alexandrite

Note that the color of alexandrite in photographs in gem report in most cases has little in common with real color of a real stone. In photos, color usually looks more attractive due to a processing in a graphic editor. You should not also completely rely on a color description specified in a gem report. In life, a stone may have a not so pure “green” and “red” color, but it will be with additional shades.

Due to color change effect features, neither photo nor video can overall describe all color. Before an alexandrite purchase, it is necessary to see a stone under different light types due to avoid frustration in its color. The following photo shows comparison between the photo in report and the real stone. On the left photo: fragment of certificate from AGL displaying the color of alexandrite under different lighting. On the video: the same sample under gemological white light and under incandescence. As you can see, green color of the stone significantly distinguishes from the color on the photo. If you have no ability to see a stone before purchase, make sure that you work with professionals who will explain to you all nuances of such an uneasy stone.

Video

Varieties

Sometimes alexandrites contain thin parallel inclusions or channels. If such stone is cut in cabochon form, it refers as alexandrite cat’s eye. If you shine a torch on the surface of cabochon, you can see thin light strip, that will move through the stone during jiggle. One of the best quality Alexandrite Cat’s-Eye stones come from Brazil.

On the photo: Brazilian Cabochon of Alexandrite Cat’s-Eye

– At the first part of the article we will tell about alexandrite color, clarity and weight. At the third part we will show you real alexandrite prices.

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