度 and 石 don't sound similar in modern Mandarin due to historical phonetic changes. They were more similar in older Chinese.度 /*[d]ˤak-s/, /*[d]ˤak/ 石 /*dAk/
Due to historical stylistic changes, this component is less similar to 石 than it was in ancient scripts.
degree, system; manner; to consider; to pass; to spend (time); measure; limit; extent; degree of intensity; degree (angles, temperature etc); kilowatt-hour; classifier for events and occurrences