This .NET class wraps the AcDbMaterial ObjectARX class. 

The Material class is used to define, store, and display material properties for shaded entities. A Material object consists of a variety of shading components, including diffuse, ambient, specular, reflection, opacity, bump, and refraction. Each component defines a different aspect of shading behavior for an entity. 

Material objects are stored in the ACAD_MATERIAL dictionary within the named object dictionary of an Database. 

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Material

Public Class Material
Inherits DBObject

public class Material : DBObject;