I cannot tell you how to distinguish between synthetic and natural
rubies. I can address the question you have regarding the valuation
of the by the appraiser:
There are a number of producers of synthetic corundum - the best
known being Chatham (http://www.chatham.com). Chatham's prices for
rubies ranges from $240.00 per carat to $900.00 per carat (retail)
depending on quality and size. There is now a producer that is
creating corundum of a quality that can be as good as the best that
Chatham offers at prices that are astoundingly low.
From one supplier the price for rough ruby is as low as 6 cents a
carat to as much as 6 dollars a carat. If you purchase the same
stone as cut stones, the price jumps to about 10 times the rough
carat price. The pricing of the rough depends on the process used to
create the rough with flame fusion being the cheapest and
hydrothermal being the most expensive. The appraiser may not be
aware of the newer materials and thus basing the value of the Chatham
I have personal experience with the newer materials; I just finished
a pearl and ruby necklace for my wife that uses a 15.5 carat ruby
heart for the centerpiece - the ruby, according to the jeweler that
set it, has no inclusions and is excellent in cut, color and clarity.
Using the Chatham pricing, the stone should retail for almost
$14,000 - I paid $11.99 for it. The jeweler compared a 1 carat
padparadsha I had with one he has from Chatham and stated the stones
were identical in cut, quality and color - He paid $180.00 for his
stone, I paid $1.39 for mine. He was completely unaware that the
lower priced stones were available.
I do not think the extremely low prices will continue for long since
the actual producer has supposedly ceased production of corundum for
at least a year. Speculation is that this is being done in an
attempt to increase the price in the future.