Originally posted by losers.inc:
are you sure its on the left hand? what about the right hand?
Yes, having attended a few solemnisation ceremonies, I'm sure it
is on the left hand. However, due to a common misconception arising
from the Chinese saying "man left; woman right", maybe there could
be a few single women out there wearing the ring on the left
finger, and scaring away potential suitors. 
As for the right hand, there could be different meanings
(engagement, fashion, remarriage, fat left finger, etc). To know
the exact reason, you'd have to ask the lady in question
herself.