The Alexandrite
This natural alexandrite faceted gemstone is moderately included. It has an excellent natural color change from a rich green in daylight to a reddish-purple color under incandescent light as shown in the photo at left (it is 100% natural color - this natural alexandrite gem is both unheated and untreated). This shallow cut gem is windowed and faces up looking like a much larger 2 carat alexandrite gemstone with measurements of 8.5mm long x 6.3mm wide! There are faintly visible natural inclusions within it which absolutely guarantee its natural origin (GIA: Type II Gem, Clarity Grade: SI). It was faceted from a natural alexandrite crystal that was mined in Minas Gerais, Brazil. Our mineralminers.com special offer price for this natural alexandrite gem is $1260./carat x 1.13 carats = $1423.80
Natural alexandrites are available in a complete range of colors from brownish to bluish green in daylight to pink, purple, red or brownish red under incandescent light. Compared to natural gemstones, most synthetic alexandrites are somewhat more blue under fluorescent light and strongly red under incandescent light. Large clean and inexpensive stones offered as natural alexandrites are most probably synthetic or not alexandrite at all.
Gemologists study the inclusions to distinguish between natural and synthetic alexandrite. Synthetic stones may also have a lower refractive index and show more fluorescence than natural stones. Natural alexandrites should be purchased from reputable dealers and expensive stones should also be tested and certified by a well established gem lab.
Reference: www.google.com
