The question has been asked so many times that this page has been included, even tough it is somewhat of a moot point. In the simplest terms ‘yes’ it is possible, but the candidate should have shown an exemplary performance.
Only one grade should be allowed to be ‘skipped’, i.e. from a 9th Kyu to a 7th Kyu instead of the 8th Kyu.
Double grading within the Kyu ranks should only be allow to occur twice at a maximum. If a student is continually double graded then the examiner/examination panel would need provide valid reasons other than their ‘subjective’ opinion. Of course, should a Black Belt from another style or group join, who does not know the syllabus, then there is the possibility of the loophole being used.
A student beginning within the Gima-Ha U.K. group should not for example be graded from white belt 10th Kyu straight to a 7th or 6th Kyu. Care must be taken not to progress a student too quickly as the standard of the Kihon and Kata are unlikely to be met on the national level.