The developers added this to the app for us a while back - if you head to a crystal profile and scroll down to 'my specimens' you can add all of your own specimens with individual images and data for your own cataloguing purposes. It works very well and keeps everything neatly contained under each crystal profile. Also if you tap on the image at the top of a profile you can bring up other images from the web, which can be handy for getting an idea of the variations in appearances.
