[Jewelry making - Article 00143] - Re: [Orchid] Platinum vs white gold

[Peter W . Rowe]

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>            Hi All, I'm hoping to get two cents from anyone with more
>     experience than I have in working with platinum and white gold. If
>     I have identical rings cast in the two materials which is more
>     likely to bend/get a flat spot when put under pressure or knocked
>     pretty hard against something while being worn?  I know platinum is
>     much more dense but have had no real experience in comparing their
>     other properties. 

    It depends some on which alloys.  Some white golds, particularly the
    palladium white golds, can be quite soft, while some platinum alloys
    are designed for heat treatment to harden them (like the Hoover and
    Strong Platinum-SK alloys) The latter can be made springy and stiff
    and quite resistant to any deformation. But with the commonly used
    10% iridium platinum, castings tend to be relatively soft.  some of
    the other common platinum alloys are even softer.  Meanwhile, normal
    nickle based white golds, and especially the 'superwhite" 18K white
    golds are hard and stiff enough that I know at least one diamond
    setter who refuses to do certain types of setting work in those
    alloys.  Between these two types, the white gold will be MUCH more
    resistant to bending and denting and scratching. However, even
    though the platinum ring seems softer and easier to deform, it will
    resist wearing away a lot longer.  The white gold may be stiff and
    hard, but over time with wear, prongs and shanks, etc, will get worn
    thinner much faster than with the platinum, which even with dents and
    bending, might still last lifetimes.  And if the platinum is work
    hardened a bit, such as in casting the shank thicker and smaller
    than desired, and you then forge the shank up in size, thus working
    the metal,  the bending and distortion can also be greatly reduced to
    the point where it's not so much of a problem at all.  It also
    depends a lot on how delicate your design is.  If you make a size 8
    ring in cast platinum, with a shank that's 1.2 mm wide and .7 mm
    thick, this is gonna bend way out of shape before you've worn it two
    days.  Make it twice that in both dimentions, and it can be
    reasonably sturdy. Heavier still, and it won't be bending much from
    routine normal wear. And if you can fabricate significant portions
    of the ring from drawn wire and rolled sheet metal,  and the like,
    you find the distortion, bending, and denting problems are GREATLY
    reduced. Rolled and drawn metal is denser, with a finer crystal
    structure, and holds up to wear and tear a lot better than most
    platinum castings. 

Peter Rowe

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