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Testing Platinum


#1

Is there any way to test for platinum? Are there chemicals available?
(I really don’t want to buy any electronic machines.)

Doc


#2
Is there any way to test for platinum? Are there chemicals
available? (I really don't want to buy any electronic machines.) 

The color, look, (note how platinum develops a different sort of
patina than do golds, which wear down differently) density and feel
is often your first clue, and with experience, is often enough to be
pretty sure. Just touch a graver to the surface and you can tell
something about the hardness (white golds feel very different) Then,
it’s inert to cold aqua regia or any other single acid, which is
another clue. You can buy platinum testing acids, which basically
let you mix a drop of fresh aqua regia right on the metal, or on a
streak of the metal, which is more sensative. If you can heat a bit
of the metal, note that it stays bright for most platinum alloys, or
for cobalt, gets a light blue oxide, and the cobalt alloy is also
weakly magnetic. To heat test an item that you can’t heat, use a
graver to shave off a tiny flake from somewhere, and heat that. Same
result. Won’t melt, stays bright. The trick to that is to not loose
where that tiny flake landed on your platinum soldering pad. Use a
loupe…

All in all, testing for platinum is a bit of a pain, but you can
usually at least tell if it’s a platinum alloy. The fineness or
exact alloy (other than the magnetic nature of the cobalt platinum
alloys) is pretty much something you need a good lab with more
sophisticated equipment for.

Peter


#3

Doc- You can get a platinum testing acid (aqua regia?) from Rio,
goes with touchstone testing. Won’t tell you %, alloy, etc.

Jim
www.mardonjewelers.com


#4

how do i identify platinum for sure from white gold rhodium etc what
specific character does it have that those others dont have for
immediate identification then We can do the sg tests etc later ie
how do i know im holding some piece of platinum

frank


#5
how do i identify platinum for sure from white gold rhodium etc
what specific character does it have that those others dont have
for immediate identification then We can do the sg tests etc later
ie how do i know im holding some piece of platinum 

The heft (it’s much heavier feeling than gold) is the first obvious
clue, but takes some experience. The color is a darker grey than
white golds or rhodium plated golds, and if it’s been worn at all,
the patina of surface wear, scratches, dings, etc, will look
different (deeper) too. Also, using a loupe to look for a quality
mark is a good plan (grin), since platinum’s resistance to wear means
that if it was stamped or marked, that mark is more likely to
survive over time than with other metals. If you have time to test
it, it’s inert to common testing acids, including cold aqua regia,
which will affect golds. If you can do a more active test, use a
graver to take off a tiny shaving. First, it feels different from
golds under a graver. Then, when you hit that shaving with a torch
flame, it won’t melt until you get it much hotter than gold would
take, and when it cools, it’s still bright. If it’s not bright,
check with a magnet, since cobalt platinum is slightly magnetic.

Peter


#6

i am playing catch up… you can test with iodine will turn black on
a pc of white jewelry if palladium if the pc turns colorless the pc
is platinum and if the pc turns brownish the 14 gold

Andy The Tool Guy Kroungold