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specific gravity test for "refined" scrap gold

The other day I visited a wholesale jeweler who also buys scrap gold and silver from the public (well, who doesn't these days).

He "refines" the old jewelry that he buys into small bars that he sells to other jewelers.

this is what he does-- he first sorts the jewelry by 18kt, 14kt, 10kt, etc., and then puts it into some kind of bowl and melts the jewelry and pours out the small bars-- maybe ten ounce bars it looks like.

so what he is actually selling to the wholesale customers are bars of 18kt or 14kt gold. he is not refining back to pure gold.

during the "refining" process, his guys will sprinkle some powder into the gold thats being melted, I think he said its borax (maybe I misheard), which he says gets the impurities out of the gold.

he also has a scale with a specific gravity meter on it-- the gold is dropped into water and measurements are taken.

my question: if he is selling wholesale bars of 14KT gold, how accurate are these bars?

I'm clueless so I would appreciate your help.

thanks.

Comments

  • PerryHallPerryHall Posts: 45,301 ✭✭✭✭✭


    << <i>he also has a scale with a specific gravity meter on it-- the gold is dropped into water and measurements are taken. >>



    It only works if you know what alloy was used. Personally, I wouldn't trust those bars.

    Worry is the interest you pay on a debt you may not owe.

  • gsa1fangsa1fan Posts: 5,566 ✭✭✭
    Well if your making jewelry and marking it up 500% the gold purity probably not to big a worry.
    Avid collector of GSA's.
  • PerryHallPerryHall Posts: 45,301 ✭✭✭✭✭


    << <i>Well if your making jewelry and marking it up 500% the gold purity probably not to big a worry. >>



    Agree. And it's not like the buyer will be any the wiser.image

    Worry is the interest you pay on a debt you may not owe.

  • CaptHenwayCaptHenway Posts: 31,499 ✭✭✭✭✭
    Not all hallmarked gold is correctly marked. Some is a little high, some, perhaps a higher percentage, is a little low.

    He is sorting it by what it says, not by what it is. If you bring that to me to sell, I am going to do a scratch test and then loball the heck out of it because I have had bad experiences with melted lumps.

    TD
    Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
  • meluaufeetmeluaufeet Posts: 746 ✭✭✭
    I thought the general process was to buy, sort, smelt, assay, and sell to refiner...

    I know there are some gold scrap buyers here... maybe they will chime in...

    Here's a pretty cool guy at youtube... urban miner... 'mustangjake2074':

    mustangjake @ youtube

    He has a series on this subject. He's pretty good at getting back to questions. He has done very well over the past year.
  • this guy also does a scratch test during the sorting process. how accurate is the scratch test?

    yes, I know that gold isnt necessarily what it is stamped.

    heck, when I was a consumer reporter in LA I did countless stories about crooked dealers stamping 12kt gold as 14kt and 8kt gold as 10kt.

    will a scratch test tell the difference between 14kt and 12kt ????
  • CaptHenwayCaptHenway Posts: 31,499 ✭✭✭✭✭


    << <i>this guy also does a scratch test during the sorting process. how accurate is the scratch test?

    yes, I know that gold isnt necessarily what it is stamped.

    heck, when I was a consumer reporter in LA I did countless stories about crooked dealers stamping 12kt gold as 14kt and 8kt gold as 10kt.

    will a scratch test tell the difference between 14kt and 12kt ???? >>



    Usually.
    Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
  • PerryHallPerryHall Posts: 45,301 ✭✭✭✭✭
    How does a scratch test work? I've heard of using a touch stone and different strengths of nitric acid to determine the purity of gold but I've never heard of the scratch test.

    Worry is the interest you pay on a debt you may not owe.

  • gsa1fangsa1fan Posts: 5,566 ✭✭✭
    A Google search found this;

    "Acid/Sctratch Testing
    # Acid/scratch testing is a cheaper option among more exact gold purity tests, able to determine the purity of a sample with relatively high precision. This may be done at home by purchasing an acid-testing kit or in a professional laboratory. The test is performed in a series of trials with gold needles at varying increments of karat level. Scratch a needle and your sample against a touchstone, and apply a low-level acid that corresponds to the karat level being tested. This acid will change the color of the scratches; if the two colors match, your sample has the approximate karat level of the gold needle used in that particular trial."
    Avid collector of GSA's.
  • CaptHenwayCaptHenway Posts: 31,499 ✭✭✭✭✭
    We have a different technique. We have bottles of acid of different strengths. Take a sample of the gold by rubbing it on a touchstone. Put a drop of acid that corresponds to the fineness it is marked, or that you think it is, on one end of the rubbing. If it is 14kt gold the 14kt acid will not eat it away.

    If it does not eat away, put a drop of the 18kt acid on the other end of the rubbing. This should quickly eat the rubbing away. If so, the gold is approx. 14kt. If it eats it away slowly, it is approx. 16kt. If it does not eat it away, it may be 18kt.

    If so, verify by taking another rubbing and testing it with the 22kt acid. If it eats it away slowly you may have 21kt gold. If it does not eat it away at all, you either have 22kt gold or better (not uncommon with gold jewelry from Eastern Asia, or a fake with base metal plated with pure gold. Heft the piece to see if it feels like high-grade gold. If it has a good heft and passed the acid test, it is probably OK. If it passed the 22kt acid test but is marked 14kt and has a poor heft, it is a plated fake.

    At the other end, if the 14kt acid did eat the rubbing away, test the other end with the 10kt acid. If it does not eat the rubbing away, it is probably 10kt. If the 14kt acid ate the rubbing away slowly, but the 10kt acid did not eat it away, it is probably 12kt.

    The different karat fineness do have distinctive colors, but these can be masked by cleaning.

    I can usually tell the fineness of a chain by its heft, but this is not reliable on odd-shaped pieces.

    TD
    Numismatist. 50 year member ANA. Winner of four ANA Heath Literary Awards; three Wayte and Olga Raymond Literary Awards; Numismatist of the Year Award 2009, and Lifetime Achievement Award 2020. Winner numerous NLG Literary Awards.
  • MoneyLAMoneyLA Posts: 1,825
    Capt Henway be very careful of this: "The different karat fineness do have distinctive colors, but these can be masked by cleaning. "

    remember that 14kt gold is 58.5% gold. they can change the color by how much copper or silver or other metals they add. color can be very misleading.

    the name escapes me, but there is a style of jewelry that uses three different shades of 14kt gold. the three shades are braided into chains and necklaces.

    darn-- one of you guys ask your wife and they'll know. its a girl thing.

    usually its a strand of yellow gold, rose gold, and copper-gold. a multi-color design. remember, there is white gold that can be 14kt or 18kt.

    my wedding band is 18kt white gold. but I could have also gotten a 14kt white gold band.


  • << <i>Capt Henway be very careful of this: "The different karat fineness do have distinctive colors, but these can be masked by cleaning. "

    remember that 14kt gold is 58.5% gold. they can change the color by how much copper or silver or other metals they add. color can be very misleading.

    the name escapes me, but there is a style of jewelry that uses three different shades of 14kt gold. the three shades are braided into chains and necklaces.

    darn-- one of you guys ask your wife and they'll know. its a girl thing.

    usually its a strand of yellow gold, rose gold, and copper-gold. a multi-color design. remember, there is white gold that can be 14kt or 18kt.

    my wedding band is 18kt white gold. but I could have also gotten a 14kt white gold band. >>



    It's called tri-color gold, and was very popular in the '80s. I sold a ton of that stuff and am now buying it back to melt down.
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