The main form of the representation of a gravitational potential V for a celestial body T in outer space is the Laplace series in solid spherical harmonics (R/ r) ^{n + 1}Y_n(θ, λ) with R being the radius of the enveloping T sphere. The surface harmonic Y_n satisfies the inequality(Formula presented.)The angular brackets mark the maximum of a function’s modulus over a unit sphere. For bodies with an irregular structure σ= 5 / 2 , and this value cannot be increased generally. However, a class of irregular bodies (smooth bodies with peaked mountains) has been found recently in which σ= 3. In this paper, we will prove the exactness of this estimate, showing that a body belonging to the above class does exist and (Formula presented.)for it.