Here's why:
* Short vowel sounds are typically found in words with one syllable. The vowel sound in "stone" is the only vowel sound in the word.
* Long vowel sounds are often found in words with two syllables, where the vowel is followed by a silent "e". This isn't the case with "stone".
The vowel sound in "stone" is similar to the vowel sound in words like "hot", "lot", and "on".