Useful thread. Because you can turn shards into diamonds (2800 shards per week = 28 diamonds), you actually get 218 diamonds per week for no money or gems, just a minimal soul cost. That means it’s only about 18 weeks to get a mythic.
I buy the 50 gem pack every day, but never spend real money. That’s 640 diamonds and 8600 shards (86 diamonds) per week. That works out to 5.5 weeks to get 4000 diamonds for a mythic. The total cost after 5.5 weeks is 1925 gems and 4730 souls.
Note: I know you can only convert shards to diamonds in batches of 1000, but over time the numbers will average out.
We should not forget that 3000 shards and 150 diamonds are available weekly from Guild Tasks as well: 500 shards for each statue completed to level 8 and 25 diamonds for each one completed to level 11.
So… considering more information, I try to summerize how many diamonds a player can get in a week based on action. (Please note that all shards will be craft to diamond, without consider the 100 souls cost of 1,000 shards per 10 diamond craft)