Exchange rates

Secret Shop
Every now and then the Secret Shop will feature bundles of items. To evaluate these bundles, put their names into https://www.alchemistcodedb.com/items, and look at the gem value of each item.

For example, the Seasoned Soldier Set costs 95 gems, and contains the following:

In other words, this set costs exactly as much as buying the individual items at the store.

Meanwhile, the "Physical Attacker Rare Equipment Set" costs 100 gems, and contains the following:

So you're getting 114 gems worth of equipment for 100 gems, a 14% discount.

Similarly, the "Magical Attack Rare Equipment Set"

This bundle gives you the same discount as the "Physical Attack Rare Equipment Set".

There's a few smaller bundles too, the "Warrior Essential Equipment" costs 38 gems, and contains:

So here you get a minor 10% discount.

Veda shop
You can do a similar comparison for the Veda Coin Exchange.

So each Veda Coin is worth roughly 2 gems.