Why can't Zoro cut Seastone?


In chapter 402, page 8, Zoro and Usopp got cuffed together with a Seastone
cuff, but Zoro didn't cut it, and instead he suggested to cut one of their
hands.

At first I thought that maybe it's impossible to cut Seastone, but then I read
chapter 677 page 9, where Law can easily cut another person's Seastone cuff
(he is the only one that get caught by normal cuff). So why didn't Zoro cut
his, was it because he not strong enough?

Zoro

![Cuff'd!](https://i.stack.imgur.com/f5WMY.jpg)

Law

![Free!!](https://i.stack.imgur.com/nfqfL.jpg)




Kairoseki is as hard as diamond, as stated in Chapter 400 p 11, so it is
unlikely for Law to have cut it. However, it is a chain and nobody said that
the chain consists just of Kairoseki. It is highly likely that at most every
second chain link is effectively Kairoseki, since it is as hard as Diamond,
you could barely made it into a chain without any other material and after all
it is a rare material.




Kairoseki is as hard as diamond, as stated in Chapter 400 p 11, so it is
unlikely for Law to have cut it. However, it is a chain and nobody said that
the chain consists just of Kairoseki. It is highly likely that at most every
second chain link is effectively Kairoseki, since it is as hard as Diamond,
you could barely made it into a chain without any other material and after all
it is a rare material.

