[Jewelry making - Article 00764] - Re: [Orchid] Using platinum for the first time

[John Donivan]

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    Well, Jocelyn, I hope you are sitting down as you read this.  Since I
    didn't want to use imaginary numbers, I got a piece of 18 ga. silver
    sheet, 1 3/4" x 1 1/4" - about the weight of 2 crosses saw pierced, I
    think. 

    That piece weighed 9.6 pennyweights (1 troy oz. = 20 pennyweights or
    Dwt.).  Silver spot on Friday was $7.19, dividing by 20 is $.44/dwt. 
    
    Multiply by the weight of 9.6 and we get a cost of $4.22.  

    Spot gold was $420.90 - call it 421.  

    Doing the same thing, converting to 14kt. (spot x .585), we get
    $12.30/dwt. 

    You can estimate the weight of a piece in different metals by the
    ratio of their specific gravities, so 14k will weight 1.276 heavier
    than silver, making 9.6 dwts. into 12.24 dwts. 14k for the same
    piece. So, 12.24 dwt. times $12.30 =$150.55 for that same piece of
    sheet metal.  

    Now the sitting down part - If that sheet is platinum, it will weigh
    almost exactly twice as much, spot is $879, and there is no 14kt.
    platinum, it's just spot.  So:  9.6 dwt. x 2 = 19.2 dwt. $879/oz.
    /20 = $45/dwt.  19.2 dwt. x $45 = $864, just for that piece of sheet
    metal.  

    Lest you think there is some flaw in my calculations, let me assure
    you that there is not - bearing in mind that it's only an estimate.  

    If anything it will probably be more. If you clipped off a wooden
    matchhead, and turned it into platinum, it would be worth about $20. 
    Each stroke of a sawblade is worth a quarter.  

    I do _not_ mean to put you off - just be aware of the realities. 
    Then, that piece of sheet is only one cross, my thinking being that
    the scrap could be recycled into the second cross.  OK, the melting
    point of silver is 1760 deg. F.  The melting point of iron is 2802
    deg. F, and most steels run 300 - 500 deg hotter.  The melting point
    of platinum is 3224, but since you will be using 10% iridium plat.
    (Iridium = 4449 deg. F), it will be more like 3800 deg.  

    And, like all metals, you need to superheat it ("till the surface is
    swimming").  You need a porcelain crucible, good goggles, and you
    essentially have a miniature Sun glowing on your workbench. I think
    of silver, gold, copper, brass and bronze as being cousins - anybody
    who can work one can work the others with a minimal learning curve.  

    Platinum is not the same - Yes, you use the same tools, but in
    different ways.  I quit using a fine file, because it loads up and
    puts gouges in the finish.  I use a roughing file, and then sand it
    from there - very different from silver.  

    However, and the point of this letter - if you are reasonably
    skilled, with perhaps a little coaching, you probably could do a fair
    job with the craftsman part of it.  It is the realities of the metals
    market that many people haven't seen yet.

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