Hey! I'm new to the forums, though I've used this guide for quite some time.
Anyways, to the point; by pure coincidence, I think I found a way to get a lot of gems or other collectibles that spawn around the map. I haven't found a thread like this, but maybe someone else has found this out.
Since I was bored of living in a tiny penthouse in Brideport, I decided to build a fancy house. I finished building it, and once I started living in it, I noticed I had some insects and gems spawning in my yard! I had built my house on top of a collectible spawner.
But that's not all... After having some trouble with the Electric Fence (the visitors wouldn't want to ring the bell...) I decided to delete my whole frontal fence. I planned on dragging through the fence with the delete tool, but I accidentally missclicked and dragged my whole fence several squares into my yard using this arrow:
So now my fence was cutting through my yard, through all my plants, and RIGHT through the collectible spawners. I don't know why, but having the fence through it caused the spawners to be visible and interactable-with.
The best part is that you can also use the eyedropper tool to multiply them as much as you want, and you can have as many spawners in your yard as you wish. I am personally not abusing this bug because it's cheating in my book, but maybe some other players will enjoy it.
TL;DR: Having a fence through a collectible spawner made it visible and allowed me to copy it as much as I want,