Your Ruby and Diamond chest pool is way too diverse.
You have runes, scrolls, shards, relics, armor, weapons, accessories and spells(ore and food as well) all packed into these things. You are basically spinning a wheel with hundreds of thousands of different outcomes. Most of which is against the player.
Seriously. With how slowly we get keys and how packed these chests are… it’s not greatly condusive to spend money on what would be nearly be junk most of the time.
Two things should change.
Chest loot pool needs to shrink. Having a diamond chest with a loot pool of what amounts of a couple hundred different items doesnt help the player, more so that odds they will get a common or uncommon item.
2nd, the chest system needs some kind of pity system. Players want to see some progress as they play. Pity system two folds helps in two ways. Guaranteed power progress, and knowing that money spent will yield greater success in improving my point in the game. You will see greater spending in PQ3 with a pity system in place.
Either way, the chest system as it stands will only drive people away from the game in the long run.