I know sea prism stones are extremely hard and can't remember any moment where I have seen anyone to cut or break them. If someone is cuffed with them and he or she happens to be extremely powerful and not a devil fruit eater can he or she break it? Can a swordsman cut it?

2 Answers 2


So far in the series, we have not had any instances where seastone was directly broken apart, whether with brute force or with a weapon like a sword. In cases where characters like Robin or Ace were restrained with seastone handcuffs, they were unlocked using the keys. Whether it can be done remains an open question, as we have seen both Zoro and Mihawk cut through other extremely solid objects in the past.

However, the mineral itself is not indestructible even though it is said to be as hard as a diamond. This is evident because the Marines are able to shape it into a variety of items like handcuffs, prison bars, weapons (like Smoker's sword) and even use it to coat the bottom of ships to escape Sea Kings. You can find the other limitations we know about seastone in the wikia.

In the latest manga chapters, we come to know that seastone may have originated

in Wano, and that there exist craftsmen with expertise in working with the mineral.


Silver rayleigh breaks it to release mermaid girl and later luffy breaks it in wano arc prison.

  • I thought it was destroying the device itself, not directly destroying the stone.
    – story ks
    Jun 20 at 5:25
  • 1
    Just to note, in chapter 936 where they start the Grand Sumo Inferno, Queen removes their seastone handcuffs. What Luffy breaks is an explosive collar (similar to the one used on Camie and broken by Rayleigh), and so far there has been no mention of it containing seastone. In fact, based on panels in chapter 939 and 944, Luffy was able to stretch his arms with the collars, so they are unlikely to be seastone. Personally, I wouldn't be surprised if his advanced haki worked on seastone though. Jun 20 at 13:02
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    – Gagantous
    2 days ago

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