[Jewelry making - Article 01045] - Re: [Orchid] Retipping sterling prong

[Peter W . Rowe]

========[ Invite a Friend - http://www.ganoksin.com/invite.htm  ]========


>      J.S. It is possible that there was a small area of grease or
>     other contaminate on the surface of the stone and it 'burned' into
>     the surface.  This sometimes happens with diamonds which are very
>     attractive to grease. 

    Don, the situation with diamonds and heating is quite different from
    corundum and heating.   Diamond can burn, so it needs to be protected
    from oxygen, usually with a coating of boric acid or flux.  And
    carbon sources like grease or dirt that can burn onto the surface can
    also start the diamond reacting as well, making it easier to damage
    if it's not clean.  Corundum, however is already an oxide, and a
    pretty stable one at that.  So exposure to oxygen during heating
    won't hurt it.  Reducing conditions, on the other hand, CAN.  And
    the same flux which will protect  diamond, can damage a corundum,
    since the fluxes we use are intended to dissolve metal oxides. 
    Corundum is aluminum oxide, so the flux etches it. 

    Been there.  Done that.  Couldn't afford the T-shirt 'cause I was
    paying to repolish the damn stone... 

Peter


____________________________________________________________________
T h e   O r c h i d   L i s t
Open Electronic Forum for Jewelry Manufacturing Methods and Procedures
____________________________________________________________________
Orchid FAQ:
~ http://www.ganoksin.com/orchid/faq.htm
Orchid Archives:
~ http://www.ganoksin.com/orchid/archive
Orchid Galleries:
~ http://www.ganoksin.com/orchid/gallery.htm
Invite a Friend:
~ http://www.ganoksin.com/invite.htm
____________________________________________________________________
Tips From The Jeweler's Bench - Article Archive
~ http://www.ganoksin.com/borisat/tip_sear.htm
The Jeweler's Selected Bibliography List
~ http://www.ganoksin.com/jewelry-books
Buy Orchid Jewelry:
~ http://www.ganoksin.com/shop
____________________________________________________________________
-Unsubscribe:
-Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank
____________________________________________________________________