Aleksandriitti sydän 1,9ct
Aleksandriitti / aleksandrite / alexandrite
värinvaihto kullan keltaisesta vihreään
Alkuperä (todennäköinen) : Tansania / Tunduru
Paino ( ct noin ) : 1,9ct
Mitat ( mm noin ) : 7,5 x 6.5 x 4,9
Hionta : viistehiottu
Kirkkaus : eye clean
Erinomainen Erittäin hyvä Hyvä ”kakkosluokkaa”
Ominaista : voimakas värinvaihto, kuten kuvassa
|Alexandrite was discovered in 1830 in the Ural mountains of Russia. Alexandrite is also found in Sri Lanka, Brazil, India, Tanzania, Zimbabwe, and most recently in Madagascar. The alexandrite variety of chrysoberyl is one of the rarest and most sought after of all gems.|
|Color Key:||Color changing from green to red.|
|Refractive Index:||1.741 - 1.760|
|Ocurrence:||Tanzania, India, Russia, Madagascar, Sri Lanka, Zimbabwe, Zambia.|
|Sign of the Zodiac:||Gemini|
|Month of the year:||June|
|Alexandrite is the name given to chrysoberyl which changes color due to the light source under which the stone is being observed. The two colors are usually blue-green in daylight and purplish-red under incandescent light. Stones with a weak change or better are identified as alexandrite while stones with a faint change are considered to be chrysoberyl.|
What to look for in alexandrite?
First and foremost, we need to look at the quality and strength of the color change. A strong change where the colors are bright and attractive under any kind of light is most desirable. Many stones are either a beautiful green in daylight or a nice pinkish red under incandescent light but they are less often attractive under both light conditions. However, since alexandrite is so rare, even stones with a weaker or a less attractive change are still valuable. We grade color changes as faint, weak, moderate, or strong.
Clarity, cut, and size are the next most important considerations after color. Large stones are always rare and as a result more valuable. Cutting and proportions are important but a careful balance between weight retention, shape, color change and, careful positioning of unremovable inclusions is required to produce the most valuable stone. A poorly cut 1ct.+ stone may be worth more than a perfectly cut .90ct. stone so cutting and preforming require careful attention in order to maximize yield and value.
Which alexandrites are best?
Although Russian alexandrites have the most historical value, fine stones are available from several other deposits. Brazil, India, and Tanzania produce the bulk of today’s production but alexandrites are also found in Sri Lanka and Madagascar. Top stones are extremely rare but all of these deposits occasionally produce exceptional stones. Brazilian stones typically show the best reds under incandescent light but Indian stones are well known for their superior bluish green daylight colors. Tanzania and Madagascar seem to produce the largest stones and some of the stones are exceptional. There is currently hardly any production of Russian stones.
What colors should we look for?
There is no fixed rule about this. Some dealers look at the red incandescent color and price the stones based on the intensity of the red. In our opinion, both the daylight greens and the incandescent colors should be attractive and hightly saturated if possible. The srength of the color change change is the most important factor affecting the value of alexandrites. The GIA grades the following colors as top in daylight, G 5/2 (medium slightly grayish green) and vslbG 5/2 (medium slightly grayish very slightly bluish green). Under incandescent light, R 5/3 (medium very slightly brownish red) and slpR 5/3 (very slightly brownish slightly purplish red) are considered to be the best colors. Some stones may only look good in daylight or only under incandescent light and they should be less expensive. Finally, it is the buyer that will wear the stone so the colors he or she likes are the most important.