Testing Silver bullion

[adamg1983]

Hello all

 

I have a couple of 250g .925 bars, whats the best way to test them?  They are fairly shinny so dont want to damage them too much.  My friend has an acid testing kit and I have a rare earth magnet.  the magnet works as it should according to youtube.  Should I also use the acid?  

 

How else do others test their silver?

 

Thanks Everyone  

[SilverPirate]

Weigh them, There is an ice cube test on you tube i have never done it though,

[adamg1983]

So if it weighs 250g you would assume its .925 silver?  

 

i've just tested it with ice and it does seem to melt faster than the one not on ice. 

[Danny-boy]

Weighing bars, especially sterling probably won't tell you much due to unknown dimensions.

Unless they are collectible, acid spot them. If they are collectible, specific gravity test them.

Or get a jeweller to XRF them.

[adamg1983]

I will use the acid test later - I've just been doing a little reading on XRF testing, does it only x-ray through a small layer?  So if for example the bar was pretty big, say 500g or 1kg but were filled with a lump of something in the middle would it show up? 

[Danny-boy]

I will use the acid test later - I've just been doing a little reading on XRF testing, does it only x-ray through a small layer? So if for example the bar was pretty big, say 500g or 1kg but were filled with a lump of something in the middle would it show up?

Not generally.

[ChrisSilver]

I will use the acid test later - I've just been doing a little reading on XRF testing, does it only x-ray through a small layer?  So if for example the bar was pretty big, say 500g or 1kg but were filled with a lump of something in the middle would it show up? 

I thought It measured the density. And then you compare against the known density of silver.

But reading here, it seems like it does it slightly differently: http://www.oxford-instruments.com/businesses/industrial-products/industrial-analysis/xrf

I know know for sure that it is a non destructive method of testing.

There is also another machine which is awesome, that measures the conductivity of the metal in question:

[HawkHybrid]

sg test is probably one of the most reliable but

you do have to submerge the whole thing in

water. it's always a good sign if you feel the tug

whilst trying to hover move a magnet across the 

surface.

 

acid is destructive and thick plated items are

rumoured to pass that test.

 

HH

[Pete]

If the bar is thick layer plated then the acid test will pass BUT you will not be certain of the inner material.

You will also create a damage spot on your nice bar.

The weight is a good indicator but often with bars the dimensions are not as precise as a coin so you may not be able to tell if it is slightly oversized to compensate for a base material.

My recommendation is to measure the specify gravity - the Eureka experiment !

[sovereignsteve]

As I understand it, SG and weight is only really useful for testing gold as cupro-nickel is pretty much the same density as silver, whereas gold is heavier than almost anything you could use as a practical substitute.

[HawkHybrid]

cupro nickel should be 8-9k, silver is ~10.5k or more than 15% more

dense. gold on the other hand is virtually identical to tungsten in

density.

 

HH

[TCSilver]

So if it weighs 250g you would assume its .925 silver?  

 

i've just tested it with ice and it does seem to melt faster than the one not on ice. 

 

You can't do a weight/size test unless it's a known item.. 

 

Say you got a Silver Eagle it weighs 31.1 grams

 

So you weight your eagle and it checks out to 31.1 grams, that doesn't mean it's real

 

It has to be 31.1 grams with a thickness of 2.98 mm and a diameter of 40.60 mm = If all three check out - Then it's a good chance it's real. 

 

But it doesn't mean it's real, because you don't know if the middle is hallow, and a heavy metal is was used to even out with the right dimensions, but it's a good start. 

 

You should buy a pair of callipers 

 

I use one like this

 

http://www.ebay.com/itm/NEW-LCD-6-150mm-Carbon-Fiber-Composite-Vernier-Digital-Electronic-Caliper-Ruler-/271748514632?pt=LH_DefaultDomain_0&hash=item3f45794348

 

Their are stainless steel ones, but I like the carbon fiber, so it doesn't damage the coins. 

[Pete]

The problem with larger bars, especially gold, is the cleverness of fraud.

If you can fake a large bar of gold then you can make serious money.

Sometimes the test is destructive i.e. drilling core samples or even cutting the bar in half.

At the end of the day, gold can be smelted and re-poured as the value is weight alone and not the cosmetic appearance.

With stamped or engraved silver bars however you may be paying a significant premium for a fancy pattern.

Perhaps the only way to check is to cut it down the middle if you are concerned.

There are lots of fake silver bars in circulation so best to know your source.

I avoid bars because per ounce I can get coins for the same price.

Coins are less likely to be faked but if they are their dimensions / weights will not be correct so are much easier to test.

[HelpingHands]

Have you bought these bars recently and have a chance to return if they are fake?

 

If not, I would just wait until it comes time to sell and let a dealer test it.  No point in damaging them.

[Hookythestacker]

Could you post a picture of the bars Adam? Not that it will help establish silver content but I'd be interested to see any stamps/markings, is there anything about the bars that is making you suspicious?  Short of destructive testing, its hard to be certain if you didn't get them from a trusted source.

 

    

 

Apology, thought I'd linked a video here.

[PhilDaSilva]

Your local assay office may have an XRF scanner as they offer services to to both private individuals along with businesses and fees may vary but my local starts around £30 for the pleasure.  Specific gravity won't help much with 925 as a lot depends on the alloy metals that are included as they have changed over time with nickel no longer being used in most cases due to some people having a bad reaction to it when wearing it as jewellery, ultrasound tests won't help much as the sound velocity will also be changed when alloyed with other materials. 

 

Magnets can sometimes be fooled by heavy silver plate too as I recently found out when I was sent a plated copper ingot that was masquerading as silver, acid eventually burned through the plate exposing the copper and I got a refund. 

 

I would however recommend specific gravity tests and ultrasound veloctiy or thickness gages for testing pure silver ingots and pure gold ingots as the sound velocity should be bang on along with the thickness of the material compared to a vernier caliper measurement though technique can cause variations and its useful to have a few test items that you have verified by other methods to comnpare with, an ultrasound waveform display will usually display any different materials encased in a solid bar of gold or silver, dimensional measurements and sound velocity will also change if bars are loaded with tungsten or there are air gaps present. 

 

As said for coins of known dimensions a vernier caliper is very handy and almost foolproof if used correctly, if im looking to verify coins I take a vernier and scales as you need both dimensions and weight to be certain of a coins composition, old coins and sovereigns can be a bugger though as they do wear unevenly and may throw your measurements off very slightly. 

[sovereignsteve]

I'm pretty sure that XRF scanners only measure the surface layer so can't be definitively used for PM bricks.

Good for coins as you can couple this with size, density, weight etc.