In addition to what Chani posted above.
New Events, Stories & Special Weeks are very helpful in gathering gems....so are free re-released Stories if you haven't done them previously (especially if the double rewards actually work properly).
Diggys 1st Birthday should always give a positive gem count on multiple play throughs.....because the 45 gems earned from the quests....can provide double rewards upon completion (assuming the double rewards actually work)....quests are reset every time you play through the story....it's only Achievements & Treasures that can only be awarded once on the 1st play through only.
The gem counts on the 100 gem sale Older Unsegmented Stories spreadsheet in the relevant Wiki page.....do not include the potential double rewards that can be received on the 1st time play through Achievements (assuming that the double rewards actually work properly).
When attempting to claim the double rewards for watching ads....I have already posted some suggestions in my previous posts.
There is an extra little trick that I have recently been trialling that also seems to help....is to incorporate some patience....I find lately that if you click on the rewards the micro-second they pop-up after furiously digging &/or after closing down/logging out & re-opening/logging in the game...they are more likely to fail.
So the workaround I have now added in my previously posted regime is to practice patience.
When closing down/logging out & re-opening/logging in....you need to wait a bit longer...I usually wait at least 1 minute before trying to claim any double rewards...just to let the game have time to load fully first.
So when the double rewards automatically pop-up or before going to claim an Achievement....I wait for a least 10 seconds before clicking on the character/quest giver or Achievement reward.....then I wait again for at least 10 seconds before clicking the ad rewards button.
I also don't use the return to camp icon that automatically pops up from the quest tab after certain in game triggers....again I practice patience & return to my camp manually after waiting for at least 10 seconds....then once I'm back in my camp I again wait at least 10 seconds before clicking on the character/quest giver.
This waiting allows time for the game to finish processing it's last tasks before starting another task...like giving it enough time to finish storing/filing materials, items, food, coins, gems, precious jewels/stones & experience points into their relevant areas.
I have never bought a Gem Pack.
I have only bought a few "Event/Region/God Special Packs" in the very beginning.
I do usually buy the premium row "Special Event Passes" which do contain gems as part of the rewards.....I also like collecting the different costumes that are available in these.
When Christmas 2015 was on sale for 100 gems....I did that quite a number of times... because of the positive amount of gems it provided even on multiple play throughs.
I also make sure that I make the most of Double Materials Week so I do as many repeatable mines in my Materials Map that have "guaranteed" gems in them.
There are also some Older Stories that also give out "guaranteed" gems on repeatable mines such Christmas 2015, 2016, 2017 & 2018....which can also be activated in Double Materials Week.
I never use my gems to do any of the following:
- Refresh repeatable mines (unless on the rare occasions that I really imperatively/desperately need something in them).
- Clear out underground camp slots.
- Purchase Tiered Offers, Mystery Boxes, Green Rings, food items, speed potions etc.
- Refresh Last Tile Finder.
- Purchase Last Tile Finder (can be bought with Diggy coins instead).
- Golem (can be bought with copper instead).
- One Click Children - I don't play via the Web (can be bought with copper & Diggy coins instead).
- Holland System - I don't play via the Web (can be bought with bronze & Diggy coins instead).
I use my gems for things such as Older Stories, camp equipment, Professor Switch System, Energy Saver & Experience Booster.
If you play via the Web....there are also Themes & Decorations that can be bought with gems....Themes do also provide some camp equipment pieces.