Stone, Rock
noun
The kanji and the word are exactly the same. That means they share meanings as well.
いし
You pick up a stone. You throw it through a window. Huh. That was surprisingly easy. Do it again. Throw the stone again. It's so easy, just do it.
これは月の石です。
This is a moonstone.
川の石をコレクションしています。
I collect river rocks.
石が川に入ったら、宝石になったんだ！
The stone went into the river, and became a jewel!