Abstract. We study a canonical C * -algebra, S(Γ, µ), that arises from a weighted graph (Γ, µ), speci c cases of which were previously studied in the context of planar algebras. We discuss necessary and su cient conditions of the weighting which ensure simplicity and uniqueness of trace of S(Γ, µ), and study the structure of its positive cone. We then study the * -algebra, A, generated by the generators of S(Γ, µ), and use a free di erential calculus and techniques of Charlesworth and Shlyakhtenko, as well as Mai, Speicher, and Weber to show that certain "loop" elements have no atoms in their spectral measure. A er modifying techniques of Shlyakhtenko and Skoufranis to show that self adjoint elements x ∈ M n (A) have algebraic Cauchy transform, we explore some applications to eigenvalues of polynomials in Wishart matrices and to diagrammatic elements in von Neumann algebras initially considered by Guionnet, Jones, and Shlyakhtenko.