Hey there,
Its not a bad concept but it has a few issues.
First thing is that except for the water and fire there is no clear way to know whether a gem is valid or not.
There should be some kind of a manual how to tell a good gem from a bad one.
Also the prices are extremely volatile sometimes we talk double digits sometimes we talk thousands.
If you by chance manage to get a true gem, the gain on reselling is far from comparable with what the other tools cost. And it seems the other tools are the only way you can reliably tell if a gem is or is not true.
I tried to use the three tools you can buy at the begining.
I am still not sure if the scanners job is just to provide you with a list of diamond issuers or if it does anything else.
Overall the game funcions but its not much of a game as its a lottery.
I like the sound effects of the customers arriving tho. Thats neat