RARE VINTAGE 8K Solid Gold COIN. Measures in cm : 8 x 8 x 1,4. Miniature Gold coins. Note : STUNNING gold coins Collection – Pope John XXIII. The world’s smallest gold 8K coins. The measures of each Gold 8k coin : 1,1 cm (diameter) with a weigh from approximately 9/10 of a gr to 1.0 gr!! Belonging to my private collection.