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Corundum


#1

I recently recieved 8 sapphires,they are rough.2 of these
"sapphires" are a deep red,sapphires and rubies are both
corundum.rubies are red,sapphires are just about every color but
red,how would i go abot finding out if these 2 stones would be
considered rubies or sapphires?will they change once they are
faceted?please help me out here,thank you

Sincerely:Matthew Johnson


#2

Matthew,

A short answer to your question would be if they are “deep red” as
you say they will be classified as rubies. The problem of ruby
versus pink sapphire is when the colour of the stone is not
saturated and lies within the less saturated pink region. Check
out Ted Themelis’s Gemlab report number 6 at

http://www.ganoksin.com/borisat/nenam/gemlab6.htm

As far as the cutting goes, it shouldn’t alter or affect the
colour very much, but I will leave the facetors amongst us to type
a response to this as I am sure they know best.

all the best - Nick
(Bahrain)


#3

Hi Matthew,

If the piece of rough is color zoned (color not evenly distributed
throug h the stone), locate the color/shade you want the stone in
the culet. Concentaing the desired color in the culet will have the
biggest impact o n the finished stones color appearance.

If the stone is a uniform color cut for maximum weight retention
or to eliminate any objectionable inclusions.

Good luck!

Dave


#4

All, An ORCHID member sent me to this website. I will pass it on to
you along with an ancient quotation about gemstone treatments.

http://www.ruby-sapphire.com/home.htm

Ruby and sapphiRe: gemology writings from Richard W. Hughes

…Moreover, I have in my library certain books by authors now
living, whom I would under no circumstances name, wherein there are
descriptions as to how to give the color of smaragdus [emerald] to
crystallus [rock crystal] and how to imitate other transparent gems:
for example, how to make a sardonychus [sardonyx] from a sarda
[carnelian, in part sard]: in a word to transform one stone into
another. To tell the truth, there is no fraud or deceit in the world
which yields greater gain and profit than that of counterfeiting
gems.

Pliny [23-79 AD], from Ball, 1950, p. 195

Gerry Galarneau