Here is another installment of our "Judging Gemstones on Photo":

Alexandrite on photo: Better murky than perfect

Color changing Chrysoberyl or Alexandrite is, next to padparadscha, the most faked variety on the internet. The usual trick is to take two photos of a plain chrysoberyl and then, with a click of the mouse, change one photo into red and the other one into green, re-name it “Alexandrite” and raise the price eightfold.

Less scrupulous, but still a scam, is to take a color-shifting Chrysoberyl and tweak the color-shift into a color-change; and then raise the price fourfold.

Finally, when legitimate Alexandrite refuses to be photographed correctly (or somebody dreads the extra work) people may re-produce the actual color-change digitally. Some argue this to be OK in some cases but 100% trust and confidence in the seller is then required. Since such trust is rare the challenge of buying Alexandrite online lays in detecting digital coloring.

Here are some hints:

1. Pure green to pure red color-change has never been found in Alexandrite, much less photographed. If you see such a 100% color change on photo you better move on.

2. Average, yet still expensive, quality Alexandrite will often look blurred on photos. Day-green will be mixed with blue or yellow and/or brown, while purple is diluting the red or is even the dominant color at night. Such quality may still be rightfully called Alexandrite but it needs to backed up by a full gem report including:
a) That it is Alexandrite (not only chrysoberyl)
b) Defining the two colors
c) Judging the degree of change e.g. moderate or strong

Without certificate, photos of Alexandrite are even less conclusive than those of padparadscha or ruby.

As always: Never buy without certificate (aka report).

2. Most traders will (or should) show day and night images. It is good and normal to detect the opposite color (e.g. some red in the green day-light, or some green-blue in the night photo). Exceptions exist but they are amongst the most expensive materials on earth.

3. It is theoretically possible to shot day/night images with two different light sources but 100% identical positioning, and thus identical luster and light pattern in both photos. However, such an identical light pattern in both day and night image are a good reason to suspect digital coloring. Individually shot day and night photos will always show different light pattern.

As far as inclusions, windows, cutting, brilliancy, crystal etc. are concerned Alexandrite is no different from other Beryl’s.

Questions and comments are welcome.

Preview
Edward-great post-i do have a good interest in alexandrite-i have 2 pendents & both show classic green in daylight & purple/reddish in candlelight-all stones have been tested several times with positive verification in all cases-over the years ive bought stones that were shopped & sold not as described in sale-these were returned with no problems. Im telling u about one pendent & one stone in perticular, a 2.06ct stone i thought was russian-turns out to b Sri Lankan with good color change rated 70%-80% change, untreated, good cut & a pendent containing 15ct of alex from different world locations, also good color change. pics are tuff as u say but i would like to show these items-thanks for ur time-steve...the pic of the large pend. #12, candlelight, #39, flourescent, #14, candlelight, the top stone in #14 is the 2.06ct stone that was lab tested.

The pic of the small cross is under candlelight, the top stone is the 2.06ct stone described in the last post-steve...sorry, this is #14, my labeling did not show.