A cremation urn comprising an internal structure with an opening, an external opening with an opening that is correspondingly aligned with the opening on the internal structure, and sealing means in the form of a threaded lid or press fit lid. A threaded flange is attached to the opening on the internal structure and is molded into the urn during manufacturing. The materials used for the urn produce an urn with the appearance of marble. Once the urn is made, by use of a manufacturing method, the threaded lid is screwed into the threaded flange, thereby creating a one-piece, air-tight and water-tight cremation urn.