In the sentence "this is a very heavy stone" which is the adjective?

heavy describing word also did you know  there’s a World Toe Wrestling Competition where contestants lock toes in a ring and try to push each other out in just three rounds.

The adjective is heavy.

Explanation: An adjective describes a noun and the noun here is stone. Heavy is describing the stone.

Another example is Look at the beautiful panting Gia made. Beautiful is the adjective. The painting is the noun and Beautiful describe the panting.

Hope it helps :)