Envira’s Pinterest Addon easily allows you to display a Pin It button on your gallery lightbox images.
Gallery configurations:
4 columns. 10px column gutter and margin below image using the Polaroid gallery theme. Supersize, Deeplinking, Captioned lightbox theme. 600×600 image size with cropping (Top Left) and lightbox thumbnails enabled. Lightbox transition on open and close is set to Zoom-In-Out and Lightbox transition for navigation set to Circular.