Hmmm ... Frank might be the one to explain the technical details - I'm just guessing: I repeated your search, and got (like you) 1400 hits; there might be a limit of hits (e.g. 1400) when the search engine stops - as there are 2669 Caithness items in the database, the vast majority being paperweights (there are a few jewellery bits as well) ... so the 1400 resulting from this search are just above 50% of what's there.
If you don't know the name, you much better look at
categories - which e.g. includes a list of 984 weights with bubbles (have a look yourself at this link for other categories). Whilst the numbers in those categories will grow larger with time (and categories may therefore have to be divided), at the moment they are all below 1400.
If you don't find a weight in our
Caithness Catalogue - this does by no means imply it's not a Caithness weight! Check the
status page (seems to require login - not sure why) for what's online up to today: we have a fair backlog of images in the queue - 2669 Caithness items online today ... images of 4566 Caithness paperweights in my database at home (for comparison: the Charlton catalogue lists 2911): if you have some time to spare for this project, and some minimal computer experience, your help would be most welcome

.