Gemstones - Jewelry - Guide

Are you interested in Alexandrite?

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Looking to buy loose chrysoberyl gemstones?

Are there any other gemstones which change color?

Several other well known gemstones, including diaspore, sapphire, garnet and spinel may also change color as a function of the light source but the color change of top alexandrites is distinctive and attractive under any light conditions.

Spinels sometimes show a blue to violet color change but the change is usually weak and the stones never look like alexandrite. Turkish diaspore is being sold under the name of Zultanite and higher quality versions of this stone shift from varying shades of green in daylight to a pinkish brown under incandescent light. Only sapphires and garnets can show any real resemblance to alexandrite.

Color change sapphire

Color change sapphires are basically known to occur in two types; the ones that change from blue to purple and the ones that change from green to red. The stones that change from green to red are the ones that can be confused with alexandrite and they only occur at the deposit in Songea, Tanzania.

Although the daylight colors are usually somewhat muddy, they can be very red under incandescent light and do look similar to some of the alexandrites from the same country. Because of their similarity to alexandrites, they are referred to as alex type sapphires in Japan.

However, it is the color change garnets especially the ones from Bekily in Madagascar that most resemble alexandrite. The stones are actually a mixture of pyrope and spessartite and can show several colors depending on the light source.

Color change garnet

Although they look a lot like alexandrites they are different because they change color throughout the day. They are green or blue grey in the early morning and reddish in the late afternoon or in strong sunlight. Some of the stones are almost blue especially under fluorescent light but most of them are grey blue or green in daylight and change to red under incandescent or late afternoon light. The stones can show an excellent color change and can easily be confused with alexandrite.

Without gemological tests, the stones can be distinguished from alexandrites by the needle like inclusions that are common in them or by the way the stones change color according to the time of day. Although they look like alexandrites, these Bekily garnets will appear red in the afternoon while the alexandrites remain green. Garnets from other parts of East Africa also change color but as they normally change from brown or orange to red, they don´t look much like alexandrite.

Where can I buy, test and appraise alexandrite?

Fine alexandrites or alexandrite jewelry can be purchased from jewelers specializing in colored gemstones, at trade shows, at high end jewelry auctions, or online from websites specialized in alexandrite.

Major online alexandrite sellers
Fine alexandrites online Alexandrite jewelry online Auction houses
Multicolour Gems David Wein Christies Jewelry

The most well known gemological laboratories are listed below and all of them are equipped to test alexandrite. Most gemological laboratories only identify gemstones, they do not appraise them.

Major gemological laboratories
Gem Studies LabEuropean Gemological LaboratoryHong Kong Gems Laboratory
Zenhokyo The Russian MSU Gemological Center AIGS Gemological Laboratory
The Gem and Jewelry Institute of Thailand
GemResearch Swisslab
Gubelin Gemological Laboratories
AGTA Gemological Testing Center
American Gemological Laboratories
Gemological Institute of America
Gemological Association of Great Britain

A good appraisal takes time, expertise and a lot of experience especially with alexandrite. Jewelry stores who offer some sort of verbal appraisal aren´t doing their job properly and when appraiser´s first claim is that "you paid to much for that gemstone", then you are not getting an appraisal, but you are a victim of a practice known as low-balling. Your best choice is a professional appraiser from a major appraisal organizations, with standards of education and codes of ethics.

Major appraiser organizations
Jewellers Vigilance Canada (JVC) The National Association of Jewelry Appraisers
The International Society of Appraisers
The American Society of Appraisers
National Association of Goldsmith
The Association of Jewellery Appraisers

Alexandrite quick facts sheet

Alexandrite is a strongly pleochroic (dichroic) gemstone and will exhibit emerald green, red and orange-yellow colors and tend to change color in artificial light compared to daylight.

SynonymsAlumoberyl, Chrysberil, Chrysoberil, Chrysopal, Delametherie, Crisoberilo, Krysoberril, Oriental Chrysolite Pacific Cat´s Eye, Cat´s eye, cat eye.
VarietiesAlexandrite, Cymophane
Ocurrence: Australia, Brazil, India, Russia, Madagascar, Sri Lanka, Tanzania, USA, Zimbabwe, Zambia
Anniversary 55th(American Gem Society)
BirthstoneJune (American National Association of Jewelers )
PlanetMercury or Mars
Zodiac signLeo (Russia), Gemini (India), Scorpio (Mars)
Symbol ofLove or Jealousy
IMA statusValid Species (Pre-IMA)
Identifying characteristicsFingerprint inclusions, silk, color change
Chemical compositionCr3+: BeAl2O4
ColorGreen in daylight and red-violet in incandescent light.
Heat sensitiveNo
Optical effectsMetamerism, pleochroism
Refractive index1.745 - 1.759 (+ .004, - .006)
Specific gravity3.70 to 3.78
TransparencyTransparent to translucent
Ultraviolet fluorescenceInert to moderate red (LW and SW)