S. 69C: Unexplained expenditure-AO treated two purchase parties as bogus and made 100% disallowance-Bhawarlal Jain group-Since sales had not been doubted and without purchases, there cannot be any sales, no adverse inference could be made insofar as the export of diamonds was concerned, for which all documentary evidence was placed on record-Addition was restricted to profit element. [S. 69C, 133A, 148]