The Corpus Vasorum Antiquorum (“extensive collection of ancient vases”) was originally a print series started in the 1950s, mainly focusing on ancient Greek vases. The 300+ fascicules document specific museum collections from all over the world. The whole series is now open access. In its online incarnation, you can browse by museum,vase type, etc. There is also a search function with many specialized fields. Unfortunately, the interface isn’t really intuitive: after a few attempts, I still couldn’t get a single result for my searches. There is a manual of sorts for searching but it’s a pdf file, there are no instructions of any kind on the search page itself. This does tend to restrict the collection’s usefulness to specialized scholars only. Still, CVA is a great resource.
Best when you know where you need to look for things, but I find that searches of their combined databases (Beazley and the CVA) work fine. Beazley searches will also get you CVA refs.
That said, the whole interface and search engine needs an overhaul.