When we receive an order, we will create a 3D frame based upon the main subjects of the image, and then we place the original image on top of that frame in order to create the 3D model. Due to this, anything that is not visible in the original image will show up as empty space(what we refer to as gaps) in the 3D model. Generally, it is not possible to eliminate these gaps 100%, but the idea is to minimize the effect in the most important areas (faces, for example). To minimize this, we recommend images where all the subjects are facing directly into the camera as opposed to looking off to the side.
Ideal Image - Forward-facing, all facial features are visible:
Not Ideal Side View - Because she is looking off to the side, the parts of her cheek that are covered by her nose will appear empty in the 3D model when looking at the crystal from certain angles. The gap effect will be minimal if the crystal is looked at straight from eye level.