Alexandrite is known as the color-changing gem. In the case of the Alexandrite from Nova Era Brazil the change is most often the change from the color of an Indicolite tourmaline to the color of an amethyst. In both cases the colors are attractive. Other mining locations produce color changes that are different than Nova Era. For instance years ago when traveling to Sri Lanka we saw a few pieces of very expensive Alexandrite that went from muddy brown (with a little rusty orange) to muddy green (emphasis on muddy). The change was not startling but the colors were unattractive. About 16 years ago (or so) there was a discovery of Alexandrite in India. The colors in that case are nice to look at and resemble (to a certain degree) the colors of Morganite which are: kind of peachy to kind of pink (both phases are accompanied by a little, very little tan). The Indian stones are attractive and the color change is noticeable.
One interesting thing about the color change of Alexandrite is that most films and most cameras are partially color blind to the color-change. We ran across this issue when we wrote our first book. That was back before digital cameras and we had a devil of a time getting the color at all right. We went from Kodachrome to Ektachrome to Fuji and it was all a bust. Even now the digital cameras will tend to only see the blue or green phase and not see the other. Interesting to know how much more sensitive our eyes are in comparison to cameras and films.
Alexandrite is a color variety of the mineral Chrysoberyl. Chrysoberyl is the third hardest of the commonly known gems. Chrysoberyl is a crystalline form of Beryllium-Aluminate. As you may recall Sapphire and Ruby are collectively known as corundum. Corundum is the second hardest of the commonly known gems. Corundum is pure aluminum oxide. The second and third hardest gems both have aluminum as a major ingredient. Interesting!!!
The gem in the photo is pretty much the ultimate Santa Maria Aquamarine. A few years ago this stone came into our hands—literally—and amazed us all. A fellow I know in Brasil owns one of the mines in the mining district which produces the Santa Maria Aquamarine of fame. He made this stone available and WOW what a stone! It is about 11+ carats and about the most intense aquamarine blue we’ve seen to date. Now, that being said there is a pretty wide range of color produced from those mines down to some colors more normally found in the aquamarine range. Natural products are like that: unique gifts from Nature all according to what was happening in the Earth at the time. If that stone were available in today’s current market it would be for sale for many times the asking price of when it was produced. Why??? There was production back then and several mines and miners were active. Since then many have given up. Mines in that mining district seem to be a lot like slot machines. Put the money in and you may or may not get a reward. Many times we’ve heard about miners giving up after running out of capital and the next guy in at the mine hits a big pocket of gems right after he starts up. What a business….
As gems have become more widely known around the world spinel has become one of the beneficiaries. Always appreciated by gem connoisseurs, spinel has been gaining ground in popularity. If there had been large finds of spinel all through the years perhaps it would have been better known. But spinel is rare. How rare? That is always difficult to measure in a fragmented world market. One measure however is that large gems like our pictured stone cost thousands of dollars per-carat. This particular specimen is over 12 carats in weight. Other more widely available gems are still available for $20.00 per-carat or even less. That is probably the best measure of spinel’s rarity. It is difficult to find in the market—in large sizes, when you want it, in the cut you want and so forth—it is in better colors and larger sizes—unobtainium.
*The word “unobtainium” has been around for a few decades. One theory as to the origin of the term has it being invented by aerospace engineers as a material they would like to use but can’t find or afford in the creation of aero planes.