Elongated diamond shaped, platinum silver disc with various colored lights aligning the perimeter of the disc...

I heard an unusual humming almost at B flat minor.  I looked out the window living room window, which was just a little above ground level.  I saw cars pulled off both sides of the street on Rochester Hill road in Rochester, NH.  
Following the sound of the hum my eyes moved upward.  Approximately 25-30 feet above my front yard was a diamond shaped, platinum silver disc like object about size of a school bus just hovering.  Different colors of lights lined the perimeter of the craft and were mostly shades of blues,lavender, yellows and greens.  It seemed to remain there for a long time which was probably only about 30 minutes.
Date may be approximate, although the witness does not indicate that fact.  We have invited the source of the report to locate some of the other witnesses.  PD