Diamond Open Access is on the rise. This model of Open Access publishing doesn’t imply any payment by authors or readers. After playing a marginal role in the debates on scholarly communication, it is now attracting more attention. But what does Diamond OA mean exactly? What are its principles and values? Is it sustainable? What could be the consequences of its development for the entire scholarly communication ecosystem? Is it a threat to commercial publishers? What are the advantages and the drawbacks of this model compared to others? How does it redefine the respective roles of the various stakeholders in the landscape? What could be its impact on bibliodiversity, efficiency, costs, and quality? The Diamond OA model raises a number of new questions to be debated in the scholarly community. The Diamond Papers bring together a series of discussion papers that intend to spark new insights into these issues. The Diamond Papers should be viewed as similar in spirit to Requests for Comments (RFC) : they are not peer-reviewed, but they should be motivated by a genuine desire to engage conversations in the scholarly community on its communication ecosystem. The collection is co-edited by Johan Rooryck and Pierre Mounier, co-coordinators of the Diamas Project. Anyone interested in the scholarly communication ecosystem is invited to contribute to the collection, either by commenting on papers already published or by proposing new papers to be published on this website. Submitted papers and comments are required to follow the terms and conditions of use of OpenEdition, in particular article 6.7. All submissions that contribute to the debate sketched above are welcome. Papers can be submitted in the languages that both editors can read and understand: English, French, Italian, Latin, and Spanish.