Hi !!!
Both these names have the same origin: they could come from the Latin virdis "green" or verus/veridicus "true, sincere".
I love the name Verdiana but it is rare (in 2016 were born only 8 of them) while Viridian is its fascinating English masculine form.
WDYTO them?
if you are into etymologies I will add the passages:
1 "green" Viridis - 2 Viridius/Viridia - 3 Viridianus - 4 Viridian (English form) - 4 Viridiano/a (Archaic Italian) - 5 Veridiano/a - 6 Verdiano > Verdiana.
"true, sincere" Verus - Veridicus - Veridianus - Verdiano > Verdiana
Personal Name Lists
https://www.behindthename.com/pnl/125456