Help - Serious question - how much do these items weigh?

Question

A UK twenty pence piece (decimal)...

AND

A UK 1 pence piece (decimal)......

I've got to weigh some gold that I found today and I'm trying to estimate it's weight and therefore price. I've made some primitive scales out of a pen and steel ruler LOL. But all I've got is 1 pennys and twenty pence pieces as standards (weights). I know it will only be about 10% accurate, but that doesn't matter too much at this stage..... PLEASE HELP????

10 speedy points for the most accurate answer, and please let me know where you found out from. Thanks in advance..... JEDI KNIGHT 007 ........xxxx

Answer 1

20p UK:

Diameter 21.4mm

Weight 5.0g

Thickness 1.7mm

1p UK:

Diameter 20.3mm

Weight 3.56grms

Thickness 1.52mm - bronze

                   1.65mm - copper-plated steel

Answer 2

20p...=5.0 grams

1p...= 3.6 grams