A dear old relative passed away recently and her family gathered for the reading.............Where was the hiding place?

Question

A dear old relative passed away recently and her family gathered for the reading of the will.
The final item was the Chalk Emerald, a priceless gem.
The will bequeathed it to whoever determined where it was hidden.
The only clue was it was in a cylinder surrounded by a thousand squares.
A young lass of barely six immediately piped up saying she knew where it wad hidden and she was correct.
Where was the hiding place?