Rune of crystal working?

[Jameson]

Is rune of crystal working? I tried using C grade with lv20, but still gives penalty with the rune in inventory

[Alannah]

examples:
rune of crystal lv3 - you can use: D grade on a lvl 17 char, C grade on a lvl 37 char, B grade on a lvl 49 char
and so on
rune of crystal lv5 - you can use: D grade on a lvl 15 char, C grade on a lvl 35 char, B grade on a lvl 47 char and so on