Where did stones like diamonds emeralds rubies sapphires came from.?

Question

Where did stones like diamonds emeralds rubies sapphires came from.?

Answer 1

Actually, diamonds are carbon (as in coal) which is subjected to extreme heat and pressure for long periods of time, to become diamonds. Many times, diamond can be found down stream from old volcanoes, because they are ejected during eruptions. Other gems form in similar ways.

Answer 2

being underground for millions of years

Answer 3

Diamonds are metamorphic rock. This means that they are sedimentary rock (broken down rock "glued together by clay-ish mud) subjected to the intense heat and pressure that is deep inside of earth. It changes their structure. I believe other gems have similar attributes but are made from different materials.