This also works at the end of the game in Castle Town, but that method is a little trickier. In that case, you must have defeated Spamton NEO and you cannot have spoken to Mr. Society at the start of the game, as doing so will, for some arbitrary reason, set off a flag that prevents the shine from appearing in the hole. Otherwise, the method is exactly the same.
There seem to be other methods, at least for the Shadow Crystal, as well, but I've yet to find any reliable way to trigger them.
![](https://s2.save4k.ru/pic/qNy6j1udiaE/maxresdefault.jpg)