I've bought some gold coins from ats bullion in london but I still have a nagging doubt - I mean - how can I be sure they're real. I know fisch make some scales, but I bought two pandas because I thought they looked lovely (and china is an emerging economy) but fisch don't do scales for these.

What would the shop do if I walked in with some coins and wanted to sell them - they were all a bit fluffy and "yeah, we're registered with the british numsmatic blah" - but how does one know the coins are real??

weigh them - gold is twice as heavy as lead or silver - so a 1oz coin like a panda will be around the 34g mark - wikipedia will tell you the dimensions of the coin - if the dimensions are correct and they weigh the right amount then they are 100% real (all the other metals that weigh as much as gold are MORE expensive).

Get your coins graded. Never had to do it myself (always steered clear of gold pandas due to rumours of fakes), but find something like a NGC (Numismatic Guarantee Corporation) authorised assayer in the UK - not sure they have them here, may need to find another grading company - it'll cost a bit, but you'll find it easier to sell them on once they are graded and slabbed; you may get lucky and get a high grading, increasing the value of your coins to collectors.

anybody know how much a 1oz kruggerand weighs? - want to put mine on my mini electronic scales...

krugerrands weigh 33.930g, if your balance goes to that many decimal places.

A DECENT SITE LIKE CHARD WILL GIVE YOU THE DIMENSIONS OF THE COIN.

multiply the diameter by 0.5 to get the radius of the coin.

now use pi*r squared*h to get the volume of the coin.

you have to do a bit of magic with the fineness to get the overall percentage of gold,but what you should end up with is a figure for the density of gold in Kg/m 3 which remains constant for whichever coin you bought.

I have bought a Fisch gold coin tester and checked 17 sovereigns and 5 Krugers I have bought on e-bay one sovereign was fake, I could not tell by looking at it - I am getting my gold coins from Baird and Chards in the future. They are cheaper than e-bay anyway and e-bay is time consuming.

how much was the fisch tester? they always seem very expensive to me.

i still say that the only thing you need is a balance accurate to 2 decimal places and a ruler

hmm, measured my 1oz krugerrands - some are 34.2g - others are 34.1g

coin designs make accurate measurment difficult - esp the 'edge'

sure, but gold is almost twice as heavy as lead - any fake ones would have to be noticably bigger if they are to weigh the same.

The fake sovereign I had the diameter was too large but the weight was correct and so was the thickness but the colour is perhaps a bit coppery but again its very hard to tell.
I cannot tell that the diameter is too large even when stacked between two genuine coins.
The Fisch tester was not cheap £68 plus a bill from the postman for VAT and handling of £14. I have since seen a second hand one on e-bay that went for about £30 as I recall.
I shall not throw the fake one away as it could be under carat gold. If I go in person to Chards or Bairds I will ask them to look at it. On Chards website they indicate that with experience spotting fakes becomes much easier.

http://www.fisch.co.za/principle.html

Gold and platinum is much denser (and therefore heavier) than the common metals such as lead, brass, copper and steel that are used to make fake bullion coins.

The result is that these fake coins are either

the correct size - but underweight, or

the correct weight - but oversize, or

both underweight and oversize.

For example: A fake made from lead to exactly the same thickness and diameter as a genuine Krugerrand would be 35% lighter than the genuine coin. If made the correct weight and diameter, it would be 54% too thick.

The Fisch is a precision made instrument that checks the vital measurements of a specific coin: These are the minimum allowable weight, maximum allowable thickness, maximum allowable diameter and the shape as specified by the issuing mint.

Metals with a density comparable to gold that could be used to make a fake coin correct in both weight and size are the platinum group metals and tungsten. The price of the platinum group metals precludes their use. Tungsten is an extremely hard, yet brittle metal that would be very difficult to work into a passable fake. No tungsten based fakes of the correct specifications have been reported.

The only metals of sufficient density that could be used to make a fake platinum coin of the correct specifications are osmium and iridium. Produced in small quantities as a by-product of platinum, they are extremely hard, brittle metals which crumble to a powder if worked cold. They are both expensive and hard to obtain.

Chards have a page on gold sovereign fakes
http://www.goldsovereigns.co.uk/fakes.html

What sort of scales are you using? that does not seem a very acurate meausement, cheap scales are often not that acurate try calibrating them if it allows you to, or test the scales with a fixed weight to see if its reading correctly.

If you got your coins from a reputable dealer(one of the main dealers BNTA members) I doubt you will have fake ones. I've got a good quality set of scales but they only do one decimal place they give me a reading of 34.0 on the nine of the kruggerands and 39.9 one two of them. These were from a BNTA member and I have had them checked by another dealer, its probably just the scales.

http://www.taxfreegold.co.uk/krugerrandinfo.html