The oil fill will differ on the original and the reproduction lamps.  The lamp on the left is an original Aladdin.   Note the angle of the oil fill compared to the blue cobalt reproduction to the right.  This is one item to check when trying to certify the authenticity of a tall Lincoln drape lamp, but not all reproductions are this easy to identify.  Some have oil fills that closely resemble those of the original, so do not use this as your sole means of identification.

  The picture below shows the design on the underside of the foot of a blue cobalt tall Lincoln drape.  The prominent markings in the center of the band are referred to as the "crows foot" design and while this design can be found on both the original and the reproduction Lincoln drape lamps, it is the fine lines pointed out by the arrows in this picture that can help you distinguish between them.  This pattern of fine lines within the band containing the crows foot design will only be found on the original tall Lincoln drape Aladdin lamps.  The strong light in this picture pronounces them, but they can be very hard to detect on some lamps. A magnifying glass with a built in light is a fantastic tool to have along when looking for details like this.

  This is the true test for authenticity of the tall Lincoln drapes!  The reproduction lamps were made in two pieces, then glued together.  You can see the joint between the fount and the stem on such lamps.  Again it can be hard to detect without good lighting, but you should be able to feel the joint with a fingernail, or a knife blade, even if you can't see it.  If you find a joint at this location the lamp is a reproduction plain and simple! Looking at the photo to the left you can see that this is a one piece original lamp. If you look in the area where the arrows are pointing you can see there is no joint between the foot and the font.