Advise on frosted diamonds

Jewelry Discussion
1

HI, I am looking for on the frosting of diamonds when
they are over heated. Have you heard of this? Apparently, the surface
of a diamond, if not clean will frost when high heat is placed near
the diamond. Do you know how much of the diamond is lost to correct
this problem?

Thank you.
Shawndra Sanger
Boulder, Colorado

2 
   HI, I am looking for on the frosting of diamonds
when they are over heated. Have you heard of this? Apparently, the
surface of a diamond, if not clean will frost when high heat is
placed near the diamond. Do you know how much of the diamond is
lost to correct this problem?

Shawndra, the question isn’t whether any of us have heard of this.
it’s rather, whether there are any of us who do any commercial repair
work who have NOT had it happen at some time or other. If you’ve
never accidentally burned a diamond, then you’ve just not been doing
this long enough. (grin)

It’s not just dirty diamonds that do this. It’s unprotected ones.
This is one of the main reasons why a dip in boric acid mixed with
alcohol is so universal a method in repair work prior to heating or
soldering. . The boric acid may protect the gold from discoloration,
but that’s even less important than protecting the diamonds. (the
gold, after all, can always be pickled and repolished) If protected
by a glazed on layer of boric acid, oxygen cannot reach the surface,
and the diamond won’t burn. And yes burning is indeed what happens.
The diamond is only carbon, after all. It doesn’t burn as easily as
your charcoal block, but it does, if forced, burn. The reason the
diamonds must be clean is twofold. If dirty, the dirt, usually
organic matter, carbonizes at a relatively low temperature, and in
contact with the diamond, seems to accelerate the ease with which the
diamond is also affected. Perhaps it acts as a catalyst. Not sure
about that. But dirt certainly DOES keep the boric acid protective
covering from properly protecting the diamond, so then the dirt
allows oxygen to the diamond surface, again, giving you a frosted
stone.

Note that it does take significant heat to do this damage. Usually
the diamond will be hot enough to be visibly glowing, at least for a
moment or so. Temps below a thousand degrees or so, don’t damage the
diamonds surface. And it’s not heat placed NEAR the diamond that
matters. The diamond itself has to get hot.

As to repair, when this happens the only option is to either replace
the stone, or have the stone repolished by a competent diamond
cutter. The damage is not a surface film over the diamond, it’s
actual etching into the surface, with the polish of the stone damaged
or destroyed. Prices to repair the stones vary, but a hundred bucks
per carat seems to jog my memory as a starting point for price.
Small stones and melee may be cheaper to just replace. Save the
burned melee. once you’ve got enough of them, (including the mildly
chipped ones too, not just the frosted ones), there are cutters
who’ll buy the parcel of damaged/burned stones from you. For more
significantly priced diamonds, recutting is the option of choice.
Usually the weight loss involved is not a lot, and the dimensions of
the repolished stone will be almost the same as the original.

Peter

3

Hi Shawndra, sorry to hear about your frosting. You shouldn’t lose
more than a couple of points by having it re-polished, but it will
depend on the size of the stone.

Mike Rogers
Precious Metal Arts
finecustomjewelry.com

4

I’ve had this happen a few times. A good coating of boric acid or
the like will help prevent it. I’ve always had it on melee size
stones that I get too close to for one reason or another. I don’t
think cleanliness has that much to do with it, I’ve had it happen on
stones that are immaculately clean before heating. When the dirty
ones get burned, it is usually a black residue, and it can usually be
cleaned off. The white frosting basically means the stone is gone in
my experience. These stones are too small to be
worth having recut, at least for me.

5

You will need to remove and send the diamond to a cutter for
repolishing. Probably will not lose more than a point… Karel

6

Hi Shawndra,

I am looking for on the frosting of diamonds when they
are over heated. Have you heard of this? Apparently, the surface of
a diamond, if not clean will frost when high heat is placed near
the diamond. Do you know how much of the diamond is lost to
correct this problem?

‘Frosted’ diamonds need to be removed from the setting & repolished
to remove the ‘frost’. Genrally the weight loss isn’t great unless
they’ve really been cooked. I’ve never seen any formula for
calculating the weight loss. Because of the tool invloved (diamond
faceting machine) & skill required, you’ll probably have to send it
to a diamond cutter or someone who specializes in repolishing.

You could check the ad section of Professional Jeweler, JCK, AJM or
contact some of the trade associations for names of places to get
this done

Dave

7

It’s usually a relatively low weight loss, but there will be some as
the whole diamond should usually be repolished.

Daniel R. Spirer, GG
Spirer Somes Jewelers

8 
    HI, I am looking for on the frosting of diamonds
when they are over heated. Have you heard of this? Apparently, the
surface of a diamond, if not clean will frost when high heat is
placed near the diamond. Do you know how much of the diamond is
lost to correct this problem?

HI, Shawndra, If you have actually frosted the diamond it is gone.
There is not much you can do that I know of. I am also in the Boulder
area by the way.

Regards J Morley Coyote Ridge Studio

9

That’s right, coat it to keep oxygen from your torch from reaching
the surface of the Diamond.