After disconnecting and coming back on i found my own soulstone while still alive. I was running shroud, in phase 2, lag was very high then i disconnected.
I was even able to pick up my stone.
Not sure if it is possible to reproduce this. Should try to disconnect and connect back during a shroud, in phase two. Or experimenting it while lagging.
Look at this:
I should have tried to sell it to the skeleton vendor