The game keeps track of how many Diamonds you have gained as a score. When this score reaches certain checkpoints, your support level will increase, earning more "Support Level Bonus". This bonus stacks multiplicatively with the Lineage Level bonus.
Diamonds earned from bug refunds do not count towards your Support Level. Due to Community Competitions using the same system to reward players, many of these competition rewards in the past did not count towards the Support Level. Ray verified on the 18th of April 2018 this would no longer be the case and the following competitions will count.
On the table below you can see what you can earn for each Support Level you reach.
The Experience and Gold Boosts stack additively with most other sources (Ascension Boost upgrades, Account upgrades, Altar bonuses, Event point bonuses, Guild upgrades, and, additionally for gold, Gold Rate (the upgrade purchasable with gold) and Inferno Bonus), but multiplicatively with the Party Boost ascension upgrade.
At a support level of 7 or above, a player's collected stone will no longer be upgrade-only when leaving a guild.