Green chest could net shards. Red chest could net shards and diamonds. Vaults could award diamonds.
This would be amazing as there is no way to farm crafting materials beyond the daily dungeon.
The amounts don’t have to be crazy but it would give us a chance to farm materials if we want to.
But then you wouldn’t have to buy gems to convert into diamonds.
If only this was suggested weeks BEFORE the update was submitted for approval… 
Or how about an alternative treasure hunt game that only gives crafting rewards? Are least players have the option to choose what resources they’re playing for.
As I have said in all other similar topics, only if they are also available elsewhere. Having only one place to grind out heavily bottlenecked and time gated resources when it is the only thing relevant to your progression will overcentralize gameplay and cause burnout.