Hand cut by artisans from Tiffany style colored mirror these diamonds are versatile and practical either used whole or cut to make smaller triangles. Each diamond is 15mm wide and 25mm long. They are 3mm thick (the standard thickness of stained glass). The silvering of the mirror contains no mercury and is safe to use in closed spaces. Although the back is sealed with epoxy paint it is advised that a neutral glue is used such as pVa or test adhesive first on a small piece.