So, not about colored diamonds, but about a colored stone... 
I remember david custom designed a wicked cool alexandrite ring a while back, and it was the first time i'd read or seen anything about that stone. 
How rare are alexandrites? 
Can they be created?  Do they look the same, and have that cool color changing quality if they're lab created?
How much do they cost?
Are they always purplish or do they come in other colors like topaz'?

amazing explanation OMC!  you're the coolest, thx!  i didn't realize so many different kinds of stones change color, that is sweet.

I've not seen much Alexandrite IRL, however, I did see one of the stones David had in his office once. One really needs to see a good one in order to appreciate these gems. The not-so-good ones can be kind of dark and muddy in appearance (and if you are not careful, you will pay too much for a so-so gem just because it "is" the coveted Alexandrite).

As OMC said, this rare variety of chrysoberyl is extremely rare and pricey; one of THE most expensive of ALL colored gemstones. In fact, many consider Alexandrite to be a sort of Holy Grail of gemstones. The dominant color depends on the light source at the time (daylight looks green, tungston/candlelight looks red or brownish red). Some say it is emerald by day ruby by night. There are other color-change gems, including sapphire, tourmaline and apatite.

Like all chrysoberyl, Alexandrite is relatively hard – 8.5 on the Mohs scale – although it can be brittle.

Interestingly, it was originally found in the Urals of Russia (and named for Czar Alexander) in the early 1800's. The Urals are the location of the OTHER rare and highly coveted green gemstone, Demantoid garnet, which was found about 30 years later (guess we'll have to pack-up and head to the Urals, LOL)!

Along with the usual pricing factors for colored gems, there are unique pricing considerations for color-changers. The intensity of colors, the extreme to which the colors change, the crispness and distinctness of the change, and the purity of the two colors are factors which come into play. For example, in the best of the best, you will see a distinct, pure intense red which will change rapidly (without going through muddy intermediate colors) into distinct, pure intense green.

Also, there is color-change garnet, a brand-newbie to the gem market. I have one, however, I don't think that I have pics of the two colors (teal and raspberry red). This is a stone that a cutter sent to me when I said I was looking for something special that was "durable, clean, and collectible." I would rate this stone's talent for color-change to be on a par with most quality Alexandrite.

To be honest, I would not have chosen this variety of gem myself. However, left with a parcel of stones over the course of several days, to my surprise, I grew to love the garnet (and it was my son's favorite out of more than a dozen beautiful stones). DS and I had a blast moving the gem all around the house and outside watching it change colors. Definitely a performer and lots of fun.

One final note, all the color change gems are extremely difficult to photograph and appreciate without seeing them in person.

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...one of the reasons being that the element at the base of the colour change in many if not all the cases is chromium, which causes strong absorption/rejection of colour bang in the middle of the peak colour range of daylight. This is not only the light that changes the most: clear vs. cloudy day makes a massive difference in the extent of yellow/orange (580-590 nm) light in the environment, but it's also the peak sensitivity of the human eye, so the effect is compounded

Film (or CCD) is not quite so peaky, but while differences "to the eye" get interpolated and adjusted by that wonderful signal processor that is the brain, and we don't "see" the difference in colour, once the image is captured by the film or the sensor quite faithfully to "real" absorption/reflection, the brain cannot re-interpret it quite as easily (because the rest of the picture does not change as much).
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PS: other stones that are a pain to picture accurately are emeralds (chromium), rubies (chromium), red spinels (chromium), chrome tourmaline (chromium). You get the gist.  Funnily enough, Crocoite, which is a chromium mineral (lead chromate) with a lovely bright red colour is actually very easy to photograph well. Go figure...

Here endeth the (photochromatic) lesson. Sorry for boring you.

OMC: never boring! 

 

I know that David has been BUSY. Here's a link to the custom alexandrite ring that he produced (should go on a DBL site custom piece page!  ). The ring was exquisite... a sensational one-of-a-kind design and the rose gold was absolutely to die for!

http://coloreddiamon...g88664.html#msg88664

I like that stone a lot. Unique ring, too.

I didn't realise just how dramatic the colour change is.

I have a setting for the stone but I can't get around to doing anything about it until after we move. It doesn't photograph well I must say. I haven't seen any in person so I can't compare how it looks to a natural stone. It is the same chemical makeup as the natural stone but just made in a lab. I got mine for $89/ct and I could choose the cut and size. The natural stones are quite spendy so this was a nice fun experiment for me to do. June is my birthday and isn't Alexandrite the birthstone along with pearls?

Oh here is the setting...

Really, if you love the look and color change phenomena of alexandrite, and want to stay with a natural gem, look into the color change garnets. Currently, they are sourced from several locations. They are less pricey than alexandrite, however, I hear the prices continue to climb, some are already quite costly (and gems from certain sources fetch higher prices than gems from others)...

Oh it is a totally different stone in there Saori! I haven't set the Alexandrite yet. I should dig up a profile photo on that ring. It's a pretty one! ETA: Here it is!



Sapphires can do the color change too but I don't know how pricey or common they are to find.

They aren't particularly common, but (compared to other types of sapphires) are not expensive. Probably because the colour change is limited, and is generally from violet/purple to blue, which although nice is not as surprising as alexandrite.