Fractured Filled Ruby Went Black

Assured ruby was not fractured filled, under heat the fractures went
black. Can this be repaired?

At the shop where I work with another highly professional and
experienced jeweler, a ring was being made with diamonds and one
center ruby. The stone showed some internal flaws under
magnification and the other jeweler and I had suspicions and
trepedation about applying heat to the gem. This stone was sold for
a substantial price. To finish the setting, an unusual technique was
needed including soldering an underbezel beneath the ruby. In this
case, due to design, soldering the underbezel was chosen over hammer
setting the stone in a “tension” style mounting. Assured the stone
was untreated in anyway, the work was done and when the torch was
removed the ruby was black in previously seen fracture areas.
Apparently the stone was fracture filled with some material.

Does anyone know how if possible to restore the stone? Surely the
filling is placed into the gem as with filled diamonds. Yet, once
burnt is there any recourse to stone restoration or is this beyond

Any advice you might have will be appreciated. The sooner the
better! This is amost a desperate situation and one which should not
have happened in the first place. Thanks for any advice. Thomas.

If you wish, email me. That will be fine. Put a note like “ruby” in
the mail so I can clear it from spam. Thanks.

Thanks Ganoksin…we will look forward to any responses.

Unfortunately I can’t offer any solutions to your quandary however
this continues to prove what I have harped on a number of times on
Orchid. NO stones should be heated anymore. There are far too many
treatments today and the heat required to do work around them is far
too dangerous to use on them since no one is ever 100% certain of
what has and hasn’t been done in the past.

Daniel R. Spirer, G.G.
Daniel R. Spirer Jewelers, LLC
1780 Massachusetts Ave.
Cambridge, MA 02140

Hi Lizzie,

If the fractures were indeed filled, presumably with an organic
substance, the burnt residue will be largely carbon which is
distressingly resistant to chemical attack. So you will need to
dissolve out the carbon and perhaps other stuff, then re-seal the
fractures. This will take serious and brutal chemistry, probably in
several steps.

These steps might include immersing the ruby for several days in hot
concentrated nitric acid, then the same in hot concentrated
hydrochloric acid, checking periodically for progress. Then in hot
concentrated alkali (sodium hydroxide = lye) but I am not sure how
corundum reacts to alkalies so this would need to be researched
first. If this fails I would try molten potassium nitrate (saltpeter)
at about 500 degrees C at which temperature the potassium nitrate
will oxidize carbon, but again first researching whether the corundum
itself may react to potassium nitrate.

This is indicative only. I doubt whether you’d actually want to do
any of it. The reagents are dangerous and the outcome not assured.
But it does give you a sort of context of the steps that may be

In your specific case I’d recommend going straight to a ruby expert,
either corundum consultant Dr. John Emmett, president of Crystal
Chemistry in Brush Prairie, WA, or Richard Hughes -

Cheers & good luck!
Hans Durstling
Moncton, Canada

Keeping in mind that one cannot be certain without having the stone
in hand…

Almost ALL ruby being mined and cut today is from one location in
Burma. The material requires heat treating to develop a pleasing red
and is characteristically full of fractures. During heat treating, a
borax containing flux is used to prevent sudden temp changes. At the
temperatures necessary to develop the color (actually drive off the
blue component) the flux melts and fills surface-reaching fractures.
This borax derived material is now a glass. It does not have the
resistance to heat that clean ruby MIGHT have, and can be altered by
a torch flame, just as the filling in fracture-filled diamonds can
be altered by a torch flame, although the filling is not the same.

I know of no way to correct this, unless there is an acid that would
remove the flux…if indeed it IS a borax flux. If that were to be
accomplished, the stone would have to be re-filled. You might
contact Yehuda in NY, the developers of the diamond filling process.

I hate to quarterback this, but it is good shop practice to remove
ANY colored stone from the piece before firing up a torch. Yes, I
know you all have never had a problem before…but when you do, it’s
a big one. Maybe someone has a cure, I don’t, sorry.

Wayne Emery
The Gemcutter

Heating in a controlled environment, with the correct procedures and
atmosphere may work (ie absence of oxygen, no sudden temp changes,
temp stability and ramp, etc) fine but no one should just stick a cut
stone in front of a torch and expect good results. Yes torches get
hot, but they don’t have the controlled atmosphere, etc that special
equipment offers.


I very much appreciate the replies. The stone is not ruined,
fortunately. However, the black area greatly diminished the
reflection of light return. Strangely, the color is actually better
but the stone is much less lively. Close examination shows the black
color to directly follow a fracture area, lending substance to the
idea that some “perhaps organic” filling was used. Then again, a
shift in the structure could cause lack of light transmission but
this does look like a residue of some sort.

We have contacted the vendor who is to contact the cutter. Still,
considering all, to remove the black area seems close to impossible
and will not be attempted. The owner of the stone appears content
with the appearance as mounted and that is some relief.

I must agree about non-application to heat to any suspect stone and
now, to even those not suspect!



There are companies thsat offer “boiling” services for cleaning gunk
out of diamond fractures. I don’t know what they use or how they use
it, but know a diamond cutter who does, and I have a friend at one
of these companies, as well. If you would like me to inquire, I
will. Maybe we can all learn something from this.