You must dust very thoroughly, in that case.

[ a dumb little science joke, given what dust is made of. ]

That really is a thing, though, isn't it? Luckily for you, I have no interest in making love potions.

[ because that's what usually happens in movies?? ]

In any case, to alleviate your concerns, the piece is less important than what it tells me. Souls are all a little different, which affects the body, but it's very subtle.

[ the kind of thing you'd only pick up on when you've been in contact with enough individual souls to notice a difference. all unique snowflakes impacted (literally) by their experiences and in some cases, other souls. ]

The easy way would be to use some physical signature that's uniquely yours, but that's actually not very secure. What if someone hijacked your body or something? We had to stop using biometrics because it's too easy to grow identical body parts.

[ it could happen. ]

I figure this is much less invasive than asking to examine your soul, at least.

You're welcome to put them to the test later, if you like; if they're unravelled that easily, they aren't good enough.