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Posted

Without professional devices, what are all possible ways of testing if gold jewellery is pure and real gold, i.e. 999.9 or 24k? It doesn't matter if it's not 100% accurate but is there any way to make a good estimation?

Posted
  On 4/3/2024 at 7:45 AM, kenny1999 said:

Without professional devices, what are all possible ways of testing if gold jewellery is pure and real gold, i.e. 999.9 or 24k? It doesn't matter if it's not 100% accurate but is there any way to make a good estimation?

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You could try Archimedes' method, viz. establish the volume of the object via displacement and then weigh it, thus determining its specific gravity. This would only work for objects with a fairly large proportion of metals other than gold in them, but then that is the case for a number of the alloys used in jewellery: https://www.thoughtco.com/composition-of-gold-alloys-608016   

Posted

Pure gold is resistant to all acids, except a mixture of Hydrochloric and Nitric, called Aqua Regia.
I would think any mixture, or alloy, of gold would have its 'impurities' affected by other acids, so that might be a simple test ?

sand off a few grains, and drop some readily available Hydrochloric or Sulfuric acid on them; see if you get any bubbling action.

 

Posted
  On 4/6/2024 at 3:42 AM, MigL said:

Pure gold is resistant to all acids, except a mixture of Hydrochloric and Nitric, called Aqua Regia.
I would think any mixture, or alloy, of gold would have its 'impurities' affected by other acids, so that might be a simple test ?

sand off a few grains, and drop some readily available Hydrochloric or Sulfuric acid on them; see if you get any bubbling action.

 

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Doesn't really work.
Only the impurity atoms on the outside are exposed to the acid; the rest are effectively protected by being "gold plated".

Density is a better option.
Even this is pretty good.
https://en.wikipedia.org/wiki/Touchstone_(assaying_tool)

On a completely pointless pedantic note, there's (at least) one acid which will attack gold.
 


 

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