An oval diamond looks exquisite with a pave diamond band and hidden halo because the combination enhances its elongated shape and brilliance. The pave band, with its continuous row of small diamonds, adds a refined sparkle that complements the oval cut's sleek, elongated facets. 

The hidden halo, set beneath the center stone, creates additional layers of light and depth, further amplifying the oval diamond's shine. Together, these elements create a sophisticated and dazzling look, highlighting the oval diamond's unique form and adding extra brilliance without overpowering its elegance.