How to test pt scrap rings etc.???
- Thread starter Froggy
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jimdoc
Well-known member
Frog,
One way would be to use a torch and bring
it to red hot if it doesn't melt and comes
back to platinum color with no oxidation
that is a good check, if you aren't worried
about melting or damaging the ring if it isn't
platinum that is. Jim
One way would be to use a torch and bring
it to red hot if it doesn't melt and comes
back to platinum color with no oxidation
that is a good check, if you aren't worried
about melting or damaging the ring if it isn't
platinum that is. Jim
jimdoc
Well-known member
Yes when buying from somebody you don't want to
freak them out, or damage what they are selling.
With platinum rings, you have to watch for alot of
stainless steels that they are making rings from
won't be affected by the acid test unless you use
heat. And also they are using tungsten which is
hefty enough to confuse with platinum.
With experience you will learn to tell by the weight
of the ring. You can use specific gravity to test
also as long as there are no stones in the ring.
I have a Mizar 24 that I have never used.
I should test it out to see how accurate it is with
platinum and tungsten and stainless steel.
Jim
freak them out, or damage what they are selling.
With platinum rings, you have to watch for alot of
stainless steels that they are making rings from
won't be affected by the acid test unless you use
heat. And also they are using tungsten which is
hefty enough to confuse with platinum.
With experience you will learn to tell by the weight
of the ring. You can use specific gravity to test
also as long as there are no stones in the ring.
I have a Mizar 24 that I have never used.
I should test it out to see how accurate it is with
platinum and tungsten and stainless steel.
Jim
PRECIOUS METALS
Well-known member
buy at any jewelry supply store platinum testing solution
keith
Member
does platinum draw to magnets like iron based metals :?
aflacglobal
Well-known member
keith said:
Platinum is actually paramagnetic. That means that it can become slightly
magnetic in a magnetic field (such as near a permanent magnet), but its
magnetism disappears when the magnetic field is removed. So, platinum will be weakly attracted to a magnet.
Pawnbroker Bob
Active member
I buy pt jewelry all the time. The true acid test for pt is a pain in the a**. Most easy tests are not testing for pt but eliminating other metals leaving a limited few that are all worth $$. The hallmarks will give you additional info as well.
Pretty much any nitric test for gold will eliminate all substiutes. Always scratch test about an inch on a touchstone or back of a ceramic tile. If you believe the item to be plated you want to scratch enough to expose the base metal. Put a drop of nitric on the touchstone and the item where it was scratched. Any reaction indicates it is not pt. Pt will not react at all.
To test for pt you need fresh aqua regia AR and fresh stannous chloride soultion SnCl. AR is the only acid that will disolve pt completely and only when heated. I have done this cold many times and get a positive pt reaction. If I haven't gotten a reaction using first nitric, then AR cold you use the hot method. Here goes...
Cold. After testing with nitric, do another scratch and put a drop of fresh AR on your scratch and let sit for a few minutes. Use a paper towel or filter paper and soak up your AR that has been sitting on the scratch or the item. Put a drop of SnCl on the AR on the paper and if it turns red you have pt. Yellow or orange indicates osmium or palladium, purple is high karat gold. Little or no reaction is a greater chance for pt but you may want to do this hot.
Hot. Basically you do the same test but you heat the item or scratch and add the acid . I usually heat a ceramic tile in a toaster oven to 200+ deg, scratch the item on the tile, place a drop of ar and wait a few minutes and do the SnCl test. BE CAREFUL!! The acid will sputter if the tile is too hot!!! Toxic fumes too! You can also scratch, put a drop of ar and then heat. ( iI don't do this because the ar fumes will ruin your oven and moving the tile around with hot acid is more risk) Then do the SnCL test on paper. You may also notice the scratch may have dissolved. If the acid has evaporated add a drop of distiled water and do the test. Also do not keep ar in a closed dropper bottle because it may fume and explode!!! Use a old glass stopper acid bottle or uncapped dropper bottle. Also your AR and SnCl must be fresh. We make a new batch every week or two. I also have a small bowl with a baking soda an water soultion that I place the tiles in when done to neutrialize the acid. You can reuse the tiles by scrubbing them with Comet and rinsing clean.
Hope this helps..
Pawnbroker Bob
Pretty much any nitric test for gold will eliminate all substiutes. Always scratch test about an inch on a touchstone or back of a ceramic tile. If you believe the item to be plated you want to scratch enough to expose the base metal. Put a drop of nitric on the touchstone and the item where it was scratched. Any reaction indicates it is not pt. Pt will not react at all.
To test for pt you need fresh aqua regia AR and fresh stannous chloride soultion SnCl. AR is the only acid that will disolve pt completely and only when heated. I have done this cold many times and get a positive pt reaction. If I haven't gotten a reaction using first nitric, then AR cold you use the hot method. Here goes...
Cold. After testing with nitric, do another scratch and put a drop of fresh AR on your scratch and let sit for a few minutes. Use a paper towel or filter paper and soak up your AR that has been sitting on the scratch or the item. Put a drop of SnCl on the AR on the paper and if it turns red you have pt. Yellow or orange indicates osmium or palladium, purple is high karat gold. Little or no reaction is a greater chance for pt but you may want to do this hot.
Hot. Basically you do the same test but you heat the item or scratch and add the acid . I usually heat a ceramic tile in a toaster oven to 200+ deg, scratch the item on the tile, place a drop of ar and wait a few minutes and do the SnCl test. BE CAREFUL!! The acid will sputter if the tile is too hot!!! Toxic fumes too! You can also scratch, put a drop of ar and then heat. ( iI don't do this because the ar fumes will ruin your oven and moving the tile around with hot acid is more risk) Then do the SnCL test on paper. You may also notice the scratch may have dissolved. If the acid has evaporated add a drop of distiled water and do the test. Also do not keep ar in a closed dropper bottle because it may fume and explode!!! Use a old glass stopper acid bottle or uncapped dropper bottle. Also your AR and SnCl must be fresh. We make a new batch every week or two. I also have a small bowl with a baking soda an water soultion that I place the tiles in when done to neutrialize the acid. You can reuse the tiles by scrubbing them with Comet and rinsing clean.
Hope this helps..
Pawnbroker Bob
Thx Bob, I reckon you are the few pawnshops that really test, considering that pawnshops sell the Pt for gold prices here in Texas, I could go on a scavenger hunt with this info, what percentage of rhodium is there in a Pt jewely item, around or about figure? Thx, frog
Usually it is iridium not rhodium in platinum jewelery. Iridium adds further corrosion resistance, but most importantly, it cheapens and hardens the metal. Iridium is very hard, and the most chemically inert of all metals...if it were as useful as platinum, it'd be many times its price as iridium is very rare.
Rhodium is mainly used in plating when a bright white finish instead of that gray silver of platinum is wanted. It's a fairly tough metal, also corrosion resistant.
Easiest way for me to tell if something is platinum is by heating it...white gold will haze, Pt will not oxidize even when molten. Or look for a hallmark, probably Pt950 or Pt 900 with the balance being iridium.
Are you serious about pawnbrokers selling Pt for the price of gold?!? Damn!! I'd like to hear more about this. Please explain...
Rhodium is mainly used in plating when a bright white finish instead of that gray silver of platinum is wanted. It's a fairly tough metal, also corrosion resistant.
Easiest way for me to tell if something is platinum is by heating it...white gold will haze, Pt will not oxidize even when molten. Or look for a hallmark, probably Pt950 or Pt 900 with the balance being iridium.
Are you serious about pawnbrokers selling Pt for the price of gold?!? Damn!! I'd like to hear more about this. Please explain...
the big chain shops have employees that really do not know what they are doing, they will even buy stainless steel rings if they are stamped 18k!!!! They think they are white gold after testing, silly..... Bet you could convince them that pt is silver and really walk out with a deal!!! :lol:
Pawnbroker Bob
Active member
Hi Frog,
Lou hit it on the mark. After you have done some scratch tests you will learn to tell what is what. Plat is very soft and when touchstone scratched it goes on like a crayon. Plat with Ird is very hard and touchstone scratches like stainless.
I've been a pawnbroker for 25 years and haven't seen but a few solid rhodium pieces. Mostly vintage.
You are right about Texas pawnshops. I have a couple of friends in the biz down there. They have told me stories about sending their employees into the big corporate shops to get loans on thier gold that came out of pawn cause the big stores were lending more than melt. The public stock traded shops have to show their stockholders a large book of pawns earning interest to keep them happy. So they tend to over loan on eveything. Inventory to them is a dirty by product of lending just like a bank.
Lou hit it on the mark. After you have done some scratch tests you will learn to tell what is what. Plat is very soft and when touchstone scratched it goes on like a crayon. Plat with Ird is very hard and touchstone scratches like stainless.
I've been a pawnbroker for 25 years and haven't seen but a few solid rhodium pieces. Mostly vintage.
You are right about Texas pawnshops. I have a couple of friends in the biz down there. They have told me stories about sending their employees into the big corporate shops to get loans on thier gold that came out of pawn cause the big stores were lending more than melt. The public stock traded shops have to show their stockholders a large book of pawns earning interest to keep them happy. So they tend to over loan on eveything. Inventory to them is a dirty by product of lending just like a bank.
If you've seen any solid rhodium pieces you are beyond lucky. I'm assuming you just mean platinum plated with rhodium, as solid rhodium is something I can probably say is never seen in jewelery. Reason is its melting point: 3567F, a full 400F over platinum, which already pushes the limits for phosphate bound investments.
PB Bob,
Good to have you aboard! I recently worked out of a Texas pawn shop for 5 years. Pawnbrokers can't make mistakes. Arguably, knowledgeable pawnbrokers are the best in the world at evaluating PM objects. I'm confident that you have great precious stones skills, also.
Good to have you aboard! I recently worked out of a Texas pawn shop for 5 years. Pawnbrokers can't make mistakes. Arguably, knowledgeable pawnbrokers are the best in the world at evaluating PM objects. I'm confident that you have great precious stones skills, also.
