Murano glass is always produced by hands and so it is noticeably irregular. Hand-blown glass used in genuine Murano creations are usually composed of several layers, applied one above the other. Often Murano masters do not put their signature on vases, glasses, carafes, mirrors and chandeliers for aesthetic reasons; in that case you will have to check for other proves of authenticity such as punt marks on the base and irregularities due to the hand making process. Hand-blown glass has punt marks on the base. This is where the glass blower has released the metal rod used to shape the glass.