Diablo 3 Reaper of Souls – Blood Shard Farming (Kadala Method)
The maximum increases the base amount (500) by 10 for each level in your Greater Rift solo personal best. For example, if your very first solo Rift run was set to level 20 and successful (within the time limit), your base maximum (500) would increase by 20*10, for a new maximum of 700.