Recent experimental results on antiferromagnetic and ferromagnetic ordering in silver at nanokelvin temperatures are reviewed. The dominant interaction between nuclear spins is the Ruderman–Kittel exchange which leads to spontaneous antiferromagnetic ordering below the record-low Néel temperature TN = 560 pK. Above Tc = −1.9 nK, ferromagnetic order has been found, which is a consequence of the fact that the spin system tries to maximize its Helmholtz free energy. The ferromagnetic ordering is observed as a saturation of the susceptibility to −1, which is caused by the formation of plate-shaped domains. Except for the re-entrant form of the antiferromagnetic phase diagram at T > 0, the overall agreement between experimental and theoretical results is good.