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Smoked diamonds

Does anyone know at what temperature diamonds will get that white
film on them? You know, when you get them to hot with the torch.


They are burnt, and need to be repolished or replaced.

I don’t know what the temperature that diamonds smoke. But you must
use flux to coat the diamonds before you put the torch to them. And
be sure you use a loop and be sure they are not fracture filled.
Flux is the must do, that protects the diamond from the heat. Hope
that helps. Janine in Redding California

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Hi Margie.

I dont know the exact temperature but I have seen it happen. I tend
to use medium or easy solder if I have to work near a diamond. The
diamond needs to be cleaned before you heat it as if there is any
sort of contaminant on the stone you run the risk of this etching the
surface of the stone as well. I only use boracic acid and or borax as
fluxes. I have another flux here called Tenacity flux that I feel
etches diamonds when heated. I think its possibly a combination of
what the diamond is in contact with, how long it is heated and how
hot it is heated that is a problem. Diamonds are being cast directly
into ring mounts so they must be able to stand a reasonable amount of

You probably do this as well but I look at the risk-benefit of
heating the stone or un-setting it. If the diamond is large and worth
a lot of money I just unset it, do the work and reset it.

It depends on how clean they are, whether they are protected by
firecoat and how long you keep them hot, but essentially if they get
hot enough to glow red, you are in danger of smoking them.

Dave Phelps

About when they glow bright red. Like when plat is hot enough to

Tipping is fine to do without prolonged red heat. It should be quick
to get the solder to follow then stop, go back in if you need to

Hi Margie,

I messed around with this subject once.

Check out

Regards, Hans

I have soldered tips on gold prongs with very hard solder with no
problem as long as the diamonds were heavily coated with boric acid
and alcohol. As long as they are squeaky clean and well coated there
should be no problem unless they are treated or filled.

We have used plat solder next to diamonds but only the very lowest
like say 1000 or 1100C. It gets pretty dicey at that temp and the low
temp plat solder is not a great color match.

So if I had to pick a number I’d say around 1100 C or higher will
smoke them. When that happens they go to the diamond cutter to be re

Have fun and make lots of jewelry.

Jo Haemer

1 Like

Thanks for the replies.

What I need to do is repair some enamel in a ring that has lots of
bezel setdiamonds in it. That means I need to put the ring in the
kiln. I have done it before without a problem, but I also was
unsuccessful one time! This time Iwant to know going in to it at
what temperature they will smoke.



Diamonds will start getting smoky at around 600 deg C. Protect your
diamonds with paste from RIO it is there in their catalog.

With enameling raise your temp slowly with a soaking time for each
ramp up.

I normally unset the diamonds before firing.

Hope it helps

Old conversation, still relevant…
Clean… Clean again… and again.
There is a great blue flux available from Gamzon tool supply, it applies a very (VERY) thin film on the piece.
Since most of my focus is platinum, I have found it to be a lifesaver. It will wash off in an ultrasonic, with soap, cold !
As to solders, PMW (and i’m guessing others now) have 1000. plat solder, It’s about the same as 20K white in melt temp. The thing is, you should never see red in the stone…ever. Torch welding/soldering can be very effective for temp. control so it’s doable.
I’ve also had my cutter “Boil” stones that have been hazed. It’s his secret sauce so I don’t know the formula (OSHA would probably have a cow…) but it’s an avenue to explore with you’re local diamond cutter as well.


Try nitric acid with ventilation. Works on some. Not on others

I’ll hope not to have to try that…
But great tip,

If the haze doesn’t come off the diamond needs repolishing