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Newsletter on our latest Jewelry Tutorials and Tool Tips . We send them out about 4 times a year. A
while ago there was a discussion on Orchid (http://www.ganoksin.com)
as to whether a diamond will evaporate if subjected to high
temperatures. I took a broken diamond and while I was
casting, at the same time put it into my oven and kept it at
725C for about an hour. Nothing happened, other than the
diamond got a 'burnt' look. Much like when one burns a
diamond because it was overheated while soldering to close
to it. I then used my dental oven and heated it up to 900C
for two hours at normal atmospheric pressure and still nothing happened.
Further heating at 900C in a vacuum for 45 minutes also
produced no noticeable change. This included weighing the
stone before and after. Then I took my oxygen-propane
torch and put the diamond in a platinum crucible and heated
it to the maximum that the torch can go. That did do
something. The temperature is about 2800C (Ref)
http://en.wikipedia.org/wiki/Propane_torch
This is the broken diamond
un-heated.
And this is the diamond after
being heated by the torch. Note the rounded facets. The
pavilion looks like it has been flame polished, like one can
do with wax or Perspex. It also became a bit smaller.
This is the diamond upon further heating for about 5 minutes
at the absolute maximum that my torch can go.
Further heating. The glassy look can be clearly seen.
My conclusion: I doubt very
much that a diamond will evaporate i.e. turn into carbon di-
oxide, in a kiln used for firing Precious Metal Clay or
gold lost wax casting in the short time used for those
processes. But with a torch it will evaporate- eventually. |
