Name: Gold Bag Quest
Requirements: Ankramesh Access Quest, 50, 100 or 200 Ancient Dusts
Reward:

Gray Bag [50 Ancient Dusts]: 170-200 Platinum Coins, 0-8 White Pearls, 0-8 Small Sapphires

Green Bag [100 Ancient Dusts]: 340-430 Platinum Coins, 0-10 Small Sapphires, 0-3 Golden Ingots, 0-1 Green Gem

Gold Bag [200 Ancient Dusts]: 330-370 Platinum Coins, 1-3 Crystal Coins, 0-5 Golden Ingots, 0-1 Yellow Gem

Follow the map to find Ahmes:

Conversation:
Player: Hi
Ahmes: Hello, I'm an archaeologist, GOD Arcanis. How may I help you?
Player: ancient dust
Ahmes: We buy up all 'Ancient Dust' and offer tresaure bags from our vaults for them ...
Ahmes: The best way to get some dusts is to kill 'Sandstorm Spectre' who live in the area below ...
Ahmes: They are too strong for us so we need some help with that ... 
Ahmes: Depending on the amount of 'Ancient Dust' I can give you a random reward from our treasury ...
Ahmes: For 50 dusts you get a gray bag, for 100 dusts a green bag, and for 200 dusts a gold bag, which color do you choose?
Player: gray
Ahmes: Please, this is your reward!
Player: green
Ahmes: Please, this is your reward!
Player: gold
Ahmes: Please, this is your reward!