[Jewelry making - Article 00635] - Re: [Orchid] Re-tipping prongs setting

[GMF]

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>         Need some basics on re-tipping prongs.  I am totally clueless,
>     so any bit of info would be greatly appreciated. 

    When I accept a customers jewellery for repair I assume full
    responsibility for it. A stone can be replaced if damaged,
    fortunately this is extremely rare. The thing that can't be replaced
    is the sentimental value of the stone to the customer. 

    In Australia we call prongs settings - claw settings - same thing
    just different words! 

    A setting that requires retipping is usually many years old and is
    most likely in a ring. It is also most likely that you as the
    repairing jeweller did not make the ring, so we must not assume that
    the original jeweller followed correct soldering procedure when
    constructing the ring....the original jeweller may have used EASY
    solder to assemble the whole ring. So when retipping I only use EASY
    solder; it will provide more than enough strength for the new tips
    and also I can be quiet confident that the ring will not fall apart. 

    Not all stones can be heated, diamonds, sapphires and rubies are
    referred to as heat proof stones, they can accept soldering
    temperatures. Before commencing any work, including cleaning on a
    setting that requires retipping I inspect the stone/s for any damage
    ie; chips, pits, cracks and advise the customer accordingly. If a
    stone is cracked I will not heat it. I prefer to unset and reclaw
    then reset. 

    One important note on diamonds; do not to heat fracture filled
    diamonds. 

    Diamonds are usually the safer stone to heat, sapphires and rubies
    can present problems during heating, ie; colour changes. If uncertain
    don't heat. 

    Important: Raise the soldering temperature gradually to avoid
    shocking the stone and after soldering gradual cooling away from
    draughts. No sudden temperature changes for the stone. 

    Assuming that the stone/s are in good condition we can set about
    retipping the claws. 

    I will use a diamond as the stone in this example. The procedure
    that I generally follow is: 

    1.    Thoroughly clean the article in ultrasonic cleaner, all traces
    of dirt must be removed especially on and around stone. 

    2.    Re-inspect the stone/s. 

    3.    File old claw tops flat, parallel to crown facets, leaving
    thin layer of metal so that stone remains set. 

    4.    Prepare metal for new tips, I use flat strip a little thicker
    and wider than required. 

    5.    Another dip in the ultrasonic cleaner to remove filings. 

    6.    Attach the ring to a copper wire and dip for one minute at six
    volts in electrolytic cleaning salts (the cleaning process used in
    gold and rhodium plating). This removes finger grease from the stone.
    If any grease is on the stone the boracic (boric) acid may not adhere
    properly. 

    7.    Rinse in clean water, do not touch the stone with your
    fingers. If you do repeat step 6. 

    8.    Hold the ring shank in fire tongs and dip into boracic acid.
    (a mixture of boracic acid and methylated spirits) Keep a lid on the
    solution after use. 

    9.    Remove ring from boracic solution and ignite.. It should burn
    with a greenish flame. When the flame extinguishes a white powdery
    surface should now be on the ring. Coverage of the stone is most
    important. If there are areas on the stone not covered another
    application is required; allow the stone to cool and repeat steps 8 &
    9. 

    10.    Commence heating with a low temperature soldering flame and
    bring the boracic acid to a clear glazed state. A complete glazed
    coverage is required to prevent the diamond "burning" oxidising.
    Unprotected diamonds will oxidise in a similar way to metal when
    heated. Burnt diamond facets need to be re-polished....this can be
    costly. 

    11.    Melt solder onto the top of each claw then place the retip
    metal and control its position with a poker while heating. I prefer
    easy grade solder, less heat to the stone. As the solder melts press
    the retip metal with the poker for firm contact onto the claw top and
    stone. Take care when adding flux during soldering; liquid flux in
    contact with the stone can cause rapid cooling and may crack the
    stone. 

    12.    Monitor the condition of the boracic acid during soldering. 

    13.    When all soldering is complete allow the stone/s to cool
    slowly then pickle. 

    14.    Trim new tips, emery and polish....rhodium plate if white
    gold. 

    I have retipped both sapphire and ruby settings if the stones are in
    good condition and not high priced. High quality stones I will
    usually unset and re-claw the setting. It might take a little longer
    but with less risk. One important note when retipping sapphs and
    rubies - do not coat with boracic acid. Glazed boracic acid can etch
    the surface of these stones. 

    Applying heat to a stone is always risky. Practicing good technique
    is important. There are other good techniques used for retipping. 

    I hope that this helps, 

Graham Farr
Sydney, Australia.

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