Once you have unlocked all the blocks you need to turn all spaces to gold and you will get the jewel. Some of the gray areas on some boards are not play spaces just breaks in the board. If all the spaces are gold that have to be you should get the jewel and the board will be complete.
If this doesn't happen then you need to change the gray block to gold to complete the board. Hope this helps. Let me know.
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Gerry