by merely looking at the alleged stone, ( and i believe those stone are fabricated, man made bonded with cement), that could be hidding something....i can see some yellowish composition and that is a good sign.... but final testing is absolutely necessary....
just like the controversial "liquid gold" ............. that is another way of hiding your loot
if the stone turns to be positive with gold.... i think this is what they did....
first method - the easiest way
grind the solid gold to a powdery form then... mixed with cement,small gravel and create some naturally looking stone)
second method - the hard way
1. solid gold are melted with aqua regia....
2. nutralized the nitric acid with, like urea....then..
3. precipated the solution with some gold dropper, like sodium metabisulfite.....this drops the gold to the bottom of the sulution to become solid/powder...dried...and
4. mixed with stone and cement and fabricate a naturally looking stone......
to revert back the method....see my first post....
joe,,,examine closely the stone with magnifying glass....if you can see some yellow luster,,,,,thats is good sign