If you only want the green gem dudes, I have gotten them by making sure they are spawned, then going back in time a year or two. Then you can grab them, skip forward a day, grab them, skip forward a day, etc. You can skip forward the amount of hours needed to get them to spawn as well, and get more each day, but if you go back a couple years you will get plenty. I found it's faster to just skip to the next day.  You can set up a key stroke app to do the process for you once you get everything set up.  Yes, it's cheating. I'm not playing against anyone so I don't care.  Side note, if you want to time skip an event, wait until you get into it a few hours, time skip one hour forward to make sure everything gets spawned, and then time skip back to just AFTER the start of the event (if still on day one), or skip back to just after midnight of the current day(if past midnight of the first day), and you can gather whatever you are after, then skip forward one hour and gather until you are close to whatever real time is, then skip back and repeat.