pixel_player8655382 Hello! First: You have not wasted 500 gems, if there is a problem, it can be fixed. From your post I assume that you do know the Wiki pages and checked the maps already for anything you might have missed. If not, please do so.
Since we are all players here we cannot look into your game. If you want us to double check with you, you have to post some screenshots. When you are sure you have not missed anything and still cannot complete the quest, you have to contact support. Here is how to:
There are 3 different ways to contact PIXEL SUPPORT.
Remember to check your email spam/junk folder for replies
Do NOT send multiple Pixel support tickets in quick succession...otherwise their spambot might eat them
1️⃣ You can contact Pixel support directly through your game settings menu
2️⃣ You can also contact Pixel support directly through this link
Do NOT type in the white search box....scroll down to the categories written in BLUE.
3️⃣ You can also send an email to Pixel Support directly through this email address
If you contact Pixel Support directly via the email address below....you MUST include your player ID number....which can be found in your game settings menu