3 diamonds was easy.
5 diamonds got there in the end.
7 diamonds took ages and I had about 25 failed boxes with nothing in.
8 diamonds... stuck on this for at least 2 days. No longer failing much though, I am getting $125,000 or an item or 500R almost every time. Probably an attempt to give me false hope that it's still giving me something because it won't give me any more diamonds.