DoC-Ep6-The Aftermath-
#6 of The defenders of Crystal
so it's clear that it wasn't a dream.
Cole Willson and Slyvester had gone to sleep tired and exhausted from what had happened during their adventure in the "crystal world". Cole had gone to sleep wondering over what had happened, if he was dreaming or in some weird nightmare. However by the next morning, he had woken up to still see the necklace he was wearing from when he had left that world. It was then evidently clear, what happened wasn't a dream the necklace Cole was wearing was real and wasn't fake. It was then known that Cole Willson and Slyvester had to keep this an obvious secret and began to talk over what had happened in that other crystal world.