It probably has a reason why certificates of authenticity are not issued. I ordered a number of photographs - they are just printed on some sheets of paper (not appearing to have any value). The estimate price was indicated as € 300 - 400. When you order more than one item you need to pay for each the very high transport cost of around € 25. Customer service doesn't reply - waiting since weeks. And to get in contact with seller is only possible after payment. Some sellers are really unfriendly - because I couldn't pick up the item straight away what I communicated to the company beforehand - no reply at all. There are probably also ok sellers on the platform. In general, I don't recommend to buy anything at catawiki. And I regret not having found this website before placing a bit. The amount of 1 star responses speak volumes.