The otherwise good Obsessed Boardgamers video review incorrectly states that you collect gems left on the path only if you are the ONLY one leaving the tomb. That's correct for artifacts but not for gems. For gems, you total all the gems remaining on the path and divide them among the number of players leaving. (Although some people say you do it card-by-card; once again the rules are ambiguous: "They equally divide all the treasures that have been left on any Quest cards in the path for this round.")
Check the forums here and on Diamant - so many rules issues for a simple game in its 4th printing!!