Few gemstones are as valuable as diamonds, but alexandrite may be one of them. Alexandrite changes from blue to red under different lighting. According to Alexandrite.net, a website dedicated to the stone, alexandrites below 1 carat are more expensive than both rubies and diamonds.
Apples and Oranges
The absence of imperfections, or inclusions, is one of the hallmarks of a valuable diamond. However, as Alexandrite.net points out, alexandrites are a Type II gemstone on the Gemological Institute of America clarity grading scale. That means they tend to have small imperfections. Colored stones in general usually are not as clean to the eye as are diamonds and should not be graded as such. An "ideal," presumably more valuable alexandrite, is blue-green by day, red-purple by incandescent light.
As of May 2014, the website Awesome Gems claims an alexandrite weighing 1 to 1.99 carats ranged from $20,000 to $35,000 on the exceptional end of the clarity spectrum. An alexandrite gemstone of the same weight, and the clarity designation of acceptable, garnered $500 to $5,000. Diamonds in the 1 to 1.99 carat range with flawless round-cut color D specimens cost between $24,000 to just under $29,000. The lower ranges of clarity garnered $1,886 to $3,884.
Clarity is a defining aspect of a diamond. The difference between one clarity grade and next could result in thousands of dollars. On the other hand, an alexandrite is more valuable if its color change is dramatic and vivid. Clarity can actually weaken the color variability in an alexandrite and lessen its value.
Hard numbers and intangible aspects play equal roles for investors in either diamonds or alexandrite. Verification of authenticity is particularly important for alexandrite mined from the Ural Mountains, as those mines ceased production and the original gems are in museums. Diamond resource Pricescope underscores that while a $100,000 diamond has greater investment-potential than a $1,000 one, medium-quality diamonds go up in price proportionally faster than expensive diamonds.