We give necessary and sufficient condition that an element of an arbitrary C * -algebra is an isolated vertex of the orthograph related to the mutual strong Birkhoff-James orthogonality. Also, we prove that for all C *algebras except C, C ⊕ C and M 2 (C) all non isolated points make a single connected component of the orthograph which diameter is less than or equal to 4, i.e. any two non isolated points can be connected by a path with at most 4 edges. Some related results are given. Definition 1.2. Let A be a C * -algebra and let a, b ∈ A. a) We say that a is strong BJ-orthogonal to b, and denote a ⊥ S b if for any c ∈ A there holds (1.2) a + bc ≥ a . b) We say that a and b are mutually strong BJ-orthogonal to each other, and denote a ⊥ ⊥ S b if a ⊥ S b and b ⊥ S a. Remark 1.1. The part a) of the previous definition is from [7], and part b) from [6].