First Gold

[trojan]

info taken from another forums, this is the best method to test your metals.

Zero your scales and weigh the object you want to test, make a note of the weight. This ring weighed 3.91 grams.

Image see the first image

Place a cup of water on a set of digital scales that are accurate to two or more decimal places. I'm using a Scobby Doo cup as it's the lightest one I have that clear so you can see whats going on, but something like a plastic cup from a coffee vending machine is lighter. Heavier glass cups will tip your scales over the . Reset to Zero, on my scales this is the Tare button.

Image see the second image

Tie the object to piece of cotton of something similar, I’m actually using a bit of string that came off the netting that comes round oranges as it's very light and non absorbent. Suspended the object in the water, just below the surface so as little as possible of the string is added to the equation. Wait for the scales to settle and take the reading. In this case with the ring, it was 0.25 grams.

Image see the third image

Simple Math

(Weight of the object) divided by (weight of water displaced)

In this case :- 3.91 / 0.25 = 15.64

Metal Density
Gold 19.3
Silver 10.5
Platinum 21.4
Palladium 12.0
Copper 9.0
9ct 10.9 to 12.7
14ct 12.9 to 14.6
18ct Yellow 15.2 to 15.9
18ct White 14.7 to 16.9
22ct 17.7 to 17.8
Sterling Silver 10.2 to 10.3
950 Platinum 20.1

18ct Gold, lovely ! This is a very reliable and easy method, no chemical testing which involves making a small mark/scratch.

[davethepaint]

Thanks trojan I will try later, does the weight of the stone not come into the calculation? Cheers Dave.

[chantalpoole]

good post trojan, this is also the best and most accurate way to determine real silver rather than silver plating .Method not just good for detecting finds its also good if you buy gold coins/bullion  or silver coins/ bullion online

[Chef Geoff]

A lovely ring Dave and gold is always a great one to cross off the "yet to find" list No your right specific gravity tests won't be accurate enough on mixed materials, your best bet would just to pop in to a jewellers and ask them to test it.
Chantal gold coins can generally just be weighed the SG test was only developed and is used to test items where a volume measurement can't be accurately taken

[Dryland]

Acid testing is a heck of a lot easier than the method above, as geoff said pop into your nearest jeweller. Pity you weren't living closer or I would have tested it for you. Some jewellers use an x-ray fluoresence machine now for testing gold.

[davethepaint]

Thank's for all the helpful replies, just spoken to the assay office in Sheffield they will do an XRF test to find the carat of the ring £13.20 + £11.20 return postage it will include a letter from them with to golds to carrat content. I have been to see a local goldsmith he says its 20 carrat upwards but as the ring is small a light (2 Grm) Approx is it worth the expense of having it tested.Cheers Dave.

[Dryland]

I't's not really worth the expense Dave.A local independant jeweller should be able to test it for you free of charge or with a minimal cost, or pop it into your local ramsdens with the pretence of selling it and see if they'll test it. But for Gods sake don't accept their offer for it as it will likely be less than £7 a gram, [ allegedly ]. More and more jewellers have recently been investing in a XRF machine.

[davethepaint]

Thanks will try to find one, but I thought ramsdens was a chippy.

[Chef Geoff]

  They are Dave but how do you think they get that golden batter on their fish

[nobby]

the price on their fish you swear they are battered in gold..........GOLDFISH!!......haha just thought of that as I was typing

[davethepaint]

Right back to the serious stuff if you put 50 grs of water in a cup then suspend an object from a piece of cotton into the water the object doesn't weigh anything as its suspended in the water on the cotton. The water is still 50grms only difference is the water is displaced not added to so why the weight difference??

[nobby]

Ye that what I didn't get either

[Chef Geoff]

No Dave it's not weightless as such as it will weigh the same as it's volume of water which it's displaced so the larger, volumetric, the item the greater the displacement but you do need scales that can weigh in (min)¹/₁₀ of a gram for reliability

[davethepaint]

Thanks I have tried this 4 times now when I suspend any object in he water the scales dont change, anyway how can you measure the water thats be displaced? So I think its Ramdens for Me 

[Chef Geoff]

OK lets pretend you have two types of water the normal one and one that is solid, our liquid version is initially weighed and weighs 10 tons we now suspend our solid water in it this measures 1 cubic meter and weighs 1 ton and so displaces the same amount of water which would also weigh 1 ton so our total measurement will now be 11 tons, we divide the difference, 1 ton, by the initial weight 1 ton....1÷1=1 which is the specific gravity of water