I will present the discovery of the the most distant cluster known, JKCS041 at z=1.9. The cluster has been discovered from optical and near infrared (NIR) observations, and their nature of a fully formed cluster revealed by Chandra X-ray data. I will also show that, as matter of fact, it is easier to find clusters in the optical/NIR than in X-ray, as testified by the larger numerical density of optically selected clusters in the same Universe volume where X-ray cluster searches have been run, up to reshift 1 at least. In the second part of my talk, I will show that cluster masses derived from modern measurement of richness (n200) and from X-ray survey data (i.e. Lx) have very similar accuracies. Therefore, weight clusters is equally competitive in the optical/NIR and in X-ray, but find them is easier in the optical/NIR.